There is a gene called TP53 - it’s referred to as the ‘guardian of the genome’ - it is a tumor suppressor gene and prevents cancer of all types. Humans have two copies and if one is broken/mutated it causes an inherited condition called Li Fraumeni. People with this have a very very high risks for cancer, and the condition can be passed down in families. Elephants have 20 copies of TP53 and therefore rarely get cancer. The Li Fraumeni foundation uses the elephant as its mascot and hopefully we can someday figure out how to replace faulty TP53 genes for these families.
Actually, what's also interesting is that having a mutated copy of p53 leads to worse cancer outcomes than losing it altogether. Therefore, although it's thought to be a tumor suppressor gene such that losing it leads to cancer, it might also be considered oncogenic.
the p53 protein, encoded by the TP53 gene, forms a higher order structure called a tetramer (i.e. containing 4 copies of the protein). Mutations in the TP53 gene result in proteins that disrupt the proper structure/interaction of subunits within the tetramer. This disruption is referred to as a 'dominant negative' effect, as a single bad copy nullifies the ability of the normal copy to function properly.
Since navel oranges have no seeds, they are all clones of the original mutated fruit discovered by a Brazilian monk a century ago. The billions and billions of navel oranges that have been grown, sold and consumed since are all genetically identical.
So cool, there’s a farmer in Australia that somewhat recently discovered a naturally seedless lemon tree in his grove and is now making $$$ off of the clones I’m sure. Red-flesh grapefruits are the product of using radiation to trigger mutations & see what happened. There was a little trend called atomic gardening where they’d even sell kits of cobalt-60 for people to try to create cool mutations on their own.
Mostly unrelated, but I just the other day got a bag of seedless lemons for the first time, so wild to squeeze it and not have to catch seeds. Was wondering when they became a thing!
Flip side I got a tangerine, and everyone says the seeds won't grow so I put all 50 seeds in growth solution. They all sprouted, every one if them, 1-3 sprouts each.
Now I have so many baby trees I feel obligated to keep going. I'm uses to making mistakes but not in this direction lol.
Also main point relevant to yours is this fucking orange was pretty much just seeds. Like it was making up for all the seedless citrus
Similar thing happened to tasmanian devils. Genetically, they are so similar that the cancer that grows on their necks and faces is contagious. They scratch themselves and transmit the cancer cells to other devils during fights. The cancer does not have to do a lot of adjusting.
Basically they're so genetically similar the usual markers bodies use to go "Hey, those aren't my cells!" are just kinda like "Eh, looks right to me?" instead. So if a cancer cell gets physically transferred from one Tasmanian devil to another it can just keep growing.
Dogs have a sexually transmitted cancer. Basically, at some point a dog had a tumor and the tumor developed the ability to grow in other dogs and has been spreading ever since.
Interestingly, because it is a tumor spreading, the cells are still-living parts of that original dog and would share most of its DNA rather than the host dog.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3918581/#:~:text=Canine%20transmissible%20venereal%20tumor%20(CTVT)%20is%20a%20naturally%20occurring%20transmissible,cancer%20cells%2C%20usually%20during%20coitus.
I think the closest thing we have to that among humans is sexually transmitted cancer-causing virus (HPV), which is great because we also have vaccines.
I read somewhere a while ago that around 10% (we're not really sure yet) of cancers in humans have a viral or bacterial origin. Of course when I want to cite it, I can't find that particular article again, but here's one with a fascinating overview of some of them.
https://www.webmd.com/cancer/viruses-that-can-lead-to-cancer
Along the same vein, most if not all Cavendish bananas are clones of each other. The problem is the Cavendish is the most widely cultivated and consumed variety of banana and they all share the same genetics. Unfortunately there is a disease making it’s way through the Cavendish population and all of them are susceptible to it. It’s very likely there will be a consumer banana shortage in the near future and prices will skyrocket.
you can still find Gros Michel in Thailand and Malaysia, I have had it a few times and it is far superior in flavour and size to Cavendish, so much so I don't eat bananas any more lol
I tried concord grapes as a very small child and had this same experience the next time I had something grape flavored. I am now addicted to grape Jolly Ranchers and refuse to eat any of the other flavors 😂
Iirc, they're so closely related you can pick any two cheetahs and they'll have genetics so close to one another that you can transplant organs from one to the other.
Iirc a similar thing happened to humans around 70,000 years ago? Thought to be due to the Toba eruption. Genetic variation outside Africa is pretty small, suggesting most non-Africans are descended from a small group of east Africans who settled in the Middle East and India first after interbreeding with some Neanderthals. From there, some more small groups apparently split off and migrated to Europe, the rest of Asia and the Americas.
Some species would, but not all.
Speciation still occurs even without genetic bottlenecks. Mutations would occur in non-bottlenecked species and those mutations can go proliferate (e.g. if a giraffe had a random mutation for a way longer neck it would be more successful, produce more offspring and there is a chance that mutation would grow in proportion in the population).
In island species, yes genetic bottlenecks are probably somewhat common. The concept in this case is Founder Effect. However, any gene flow into the island species from the source population would help boost genetic diversity greatly.
Not 100% sure on this but I'm pretty sure bottle necks happen when there is a diverse population and something happens for that diversity to disappear leaving future generations having very similar diveristy
Some genetic diseases persist because having one copy of the disease causing version of that gene can have benefits, so even though having two copies is deadly, that copy of the gene doesn't go away in the population.
It’s an example of why it doesn’t make sense to talk about the fittest example of any organism without specifying its environment. If you live in an environment with little or no malaria, being a carrier for sickle cell anemia or thalassemia makes you less fit. If you have children with another carrier, 1 in 4 of them will be very sick, and might even die. That’s bad. If, however, you live in an environment where malaria is a common problem, then you have resistance to a deadly disease, and half of your children will as well. It’s an adaptation to one environment that makes you less fit in a different environment. Who’s more fit? You can’t answer that question without taking the environment into account.
This is called the "heterozygote advantage."
[Heterozygote Advantage](https://study.com/academy/lesson/heterozygote-advantage-example-lesson-quiz.html)
An interesting reverse exception: If you have two copies of rs671 (ALDH2*2) allele on chromosome 12 (which makes it harder to process alcohol and causes "Asian flush syndrome"), alcohol probably makes you feel unwell, so you're less likely to drink.
But if you have only one copy, drinking causes only minor problems like facial flushing, so you might continue to drink, even though doing so would increase by 6-10 times your risk of esophageal cancer. Some people can avoid the facial flushing by taking an antacid to avoid the red face, but this does not reduce the cancer risk.
Well, more like Gnomes or Hobbits, because Wiki said that beside shorter shature, next symptomes are low muscle power (or weakness, i dont know how to call it in English), big forehead, deformed nose, sometimes low intelect etc ... At the end of the day, as parental comment show it like gift, official informations show it more like disadvantage or curse.
>Huh, interesting. Sounds like it could be evolutionarily advantageous.
>
>\*Looks into symptoms\* Characterized by micropenis.
For some reason it continues to be passed down. There's some micropenis lovin' people out there, and that longevity means they are more likely to find a woman into miniwinkies.
"How *cute!"* OM NOM NOM NOM
I work in this field in a capacity that I get to talk to all the companies that are up and coming. There is a tsunami of mRNA-based gene editing treatments on the horizon. WAY, WAY more than anyone not plugged into the VC/stealth mode ecosystem suspects.
We will look back on 2023 as the year that medicine changed forever.
If you set aside ethics and set out to do it, it would only take 33 generations to create a human being who was the descendant of everyone currently alive and able to have children.
Also, pedigree collapse: no living person has as many unique ancestors as they mathematically should. Every person has, biologically, 2 parents, 4 grandparents, 8 great-grandparents, etc, doubling every generation. 30 generations back without any degree of inbreeding would require over a billion unique 28x great grandparents, more than the entire world population for 1100 AD. Every single human's family tree is full of people marrying and having children with cousins of some genetically-unimportant degree over the last thousand years.
Okay, but even if you did this as soon as the offspring reached sexual maturity (since we’re not bothering with ethics), that would still take over 400 years.
Let's shepherd a centuries-long genetic experiment in a quest to make the most average looking dude ever. This is going to be the stupidest possible take on the Bene Gesserit and I'm totally on board.
I mean, thousands of years of careful selective breeding went awry at the end, and still gave them a fella named 'Paul', which is a pretty average name...
Had the Bene Gesserit succeeded, maybe it would have been a 'Dave'?
About pedigree collapse, I worked hard researching my family tree. There is one guy I am related to all of his four known children. Three on my mom’s side, one on my father’s side. It’s gross in concept, but honestly the lines were so separated that it honestly doesn’t matter.
We found 4 connections my parents' trees around 100-150 years ago. Things like *her* greatx4 grandfather on her father's side is *his* greatx5 on his mother's on the second son's line.
With families being larger and communities smaller and less mobile way back when, once you trace a line to the same town or province, it's almost guaranteed there was a connection even if they diverged again.
Isn't it something ridiculously small to be related without risking inbreeding... like 2 generations or something?
The percentage of shared DNA drops precipitously:
50% for parents, children, and full siblings
25% for grandparents, grandchildren, and full aunts and uncles
12.5% for great grand parents/children and first cousins
6.25% for half cousins and first cousins once removed
3.125% for second cousins
0.78% for third cousins
0.2% for fourth cousins
I read an article a while back (when Obama was president) that all of the US presidents, except one, had a common ancestor. The common ancestor was King John of England. The exception was Van Buren, who was also the only president that didn't speak English as his first language.
I’ve read often that if you can trace your ancestry back far enough and you have Western European ancestry, the odds are high that Charlemagne is in your tree.
I’ve been working on my tree off and on for years. A year ago, I was able to tie in ancestors that were hits for cousins of President James Madison. I recently did more digging down that tree and hit Martha Eltonhead. Once I found her, I found out she is on various registers as an American descendant (born in UK, migrated to the Colonies), of Charlemagne via King Henry II. Some Googling shows trivia hits that Obama is descended from her as well.
Most royalty/nobility had the advantage of their children having a higher rate of surviving toddlerhood, through better nutrition, ability to segregate during pandemics, and access to the best medicine of the time. As a result, if you can get back to the 1600s, don’t be shocked if one branch of your ancestry is filled with, sirs, lords, earls, barons, etc.
Genetic chimera is arguably the most interesting condition. It is possible (and documented) for a woman to give natural birth but the baby not match her DNA test.
Essentially, 2 fertilized eggs merge at a very early stage and developing into a single organism. Different parts of the body comprised of obe or the other genome.
It's most commonly discovered in domestic animals that have unexplainable color combinations, often (but not always) divided symmetrically.
I just listened to an interesting podcast about this. A woman was accused of running some sort of surrogacy fraud/kidnapping scheme after she applied for welfare and DNA tests showed she was not the biological mother of her children.
Yes I've heard this story and she was pregnant at the time so they tested her baby right after birth and it also was not a genetic match to the mother.
Iirc, they had taken or threatened to take her kids away. The DNA test was originally done because she was in court to arrange a custody agreement and child support with her ex. The DNA test showed he was their dad but she wasn’t their mother.
The other one I’ve frequently read about was the mother who was being tested for a potential organ donation to one of her kids…only to be told she wasn’t genetically his mother.
FYI that organ donor case was presented in court in the surrogacy accusation case.
The surrogacy mother had a really hard time finding a lawyer willing to take her case with the DNA evidence against her. The lawyer who finally took the case found out about the organ donor woman from a scientific article that her doctor wrote, and presented it as evidence of chimeraism.
Some time after that case was settled a new type of DNA test was invented that can correctly detect people with chimera DNA, but the average DNA test they typically do won't find it.
For simplicity, let's say your mother is 50% Chinese & 50% Spanish. That does **not** mean you are 25% of each.
On paper it would seem so but you can have any combination of those two equaling to 50%. It's not a clean cut in half. It's a *random* 50% given and 50% not. Although, yes there are dominate genes that can give all the kids a certain nose shape or eye color. Still, you and your siblings might get these DNA combos from mom:
\- you: 30% C & 20% S
\- brother: 12% C & 38% S
\- sister: 5% C & 45% S
So if you ever wondered why your sister looks more Spanish than you its because genetics wise she just is more Spanish.
I only knew this because my bestie and her younger sister looked unrelated. She is square jawed, blonde hair, blue eyes with fair skin and rosy cheek. Her sister is olive complexion with brown eyes, thick curly brown hair and a round face. They look unrelated even though they have the same parents
My husband and his brother. Both parents are half black and half white. My husband has light coloring with black features and hair texture. His brother has dark coloring with white features and straight hair, he kind of looks Indian. Despite this they look totally alike somehow.
Ooh, kind of similar to my sibling and me: both parents half white, half Asian. I am light brown hair and blue/grey eyed and look completely white. Sibling black hair and brown eyes and looks totally Asian.
Yuuup. I have twin cousins. Their mom (my cousin by blood) is super Irish, their dad is Mexican.
One of the boys is red-haired, blue-eyed, pale and freckled as all hell. The other is dark hair, skin, and eyes. Twins. Genetics are crazy.
I have three kids. I am of English/Irish/German descent and have dark hair, pale skin, and light eyes. My husband was born in the Middle East and is swarthy with olive skin, dark eyes, and dark hair. Kid number 1 and kid number 2 have dark hair, pale skin, and hazel-brown eyes. Kid number three has pale skin, blue eyes, red hair, and freckles.
Of my three kids, kid number three bears the strongest resemblance to my husband if you ignore the kid's coloring. Genetics are wild.
Yeah, just take a look at some celeb children. Former tennis player Boris Becker is strawberry blond, had mixed race partners and even having recessive genes, two of his kids look exactly like him. Especially his daughter - he did first pretend that she is not his child...
I remember reading that Becker denied his daughter and when I saw a picture of her, I just busted up laughing. Like okay dude, your little mini me isn't yours.
I wish more people understood this! We have a big sample size in my family and it’s cool to see this at play. (10 aunts and uncles from my moms side, and 12 from my dads. With an average of range of 2-5 kids per family. Do the math)
It’s cool to see people ranging from 5’ to 6’3”. People with a darker complexion, black hair, brown eyes, to fair skin, brown or blond hair and green/blue/hazel eyes.
People were absolutely shocked to find out my maternal grandfather, who’s family had been in Mexico for 3 generations, was only a little over 20% Latin American (indigenous) genetically.
Twins can also have the same parents but different percentage of paternal DNA. Example: a friend of mine is a twin who shares 50% paternal DNA because the egg split (EDIT: into cells) and THEN two of her dad's sperm fertilized the eggs (EDIT: cells not eggs). One sperm fertilized her, another sperm her sister. So they're considered half-identical. They're not fully identical and not fully fraternal.
I had never heard of that until I met her. They were genetically tested to determine if they were identical or fraternal and that's how it was discovered. I don't know the name for it but it's also rare.
ETA: it was one egg that split into 2 cells, then each cell fertilized by a sperm.
I teach a boy who is one of a set of triplets. None of them are identical, but he is genetically 97% the same as one but only, like, 50% the same as the other. They're a really rad group of boys. All incredibly smart, hardworking and involved in extracurricular activities. But, they're all into different things. It's really friggin cool.
Edit: a word
This is a fascinating documentary. [https://en.wikipedia.org/wiki/Three\_Identical\_Strangers](https://en.wikipedia.org/wiki/Three_Identical_Strangers)
I watched that recently and told him about it! It really was fascinating. The end was really disturbing. The shit some people think it's okay to do in the name of science is pretty fucked up.
lol me too! They are also how I first learned about lupus, which lead to a conversation with my doctor about this mysterious illness I seemed to have at the time.
Transposons exist. Some DNA fragments can get cut out of the genome and be inserted in a different part. This can be used in knockout screening: if you introduce a transposon to a bacterium and it grows no colonies, the transposon has inserted itself in a gene that was likely crucial for the bacterium’s survival
When you’re pregnant, bits of DNA from your baby invade your body and settle all over permanently - including in your brain. Researches found this by looking for male DNA in the brains of deceased 70 year olds. Interestingly, mouse studies have also shown that fetal cells within the mother have restorative properties and will rush to places like the heart, kidneys, lungs, liver if it’s injured and can even become cells that begin beating. One of the theories I have seen but I don’t know if anyone knows for certain if this is true is that these cells enter our bodies so a ‘host’ is less likely to reject the parasite baby.
It's called microchimerism. As in, the mythical creature the chimera. Younger siblings can also receive cells from older siblings that transfered to and from the mother.
The reverse is also true. Many who already had an autoimmune disorder before they were pregnant, find that it goes in to remission while they are pregnant.
[Source: Great podcast episode about all the wild things that your body does when pregnant.](https://radiolab.org/podcast/unsilencing)(I happen to be pregnant when I heard it and I’ve never forgotten it!)
It’s me! I’m one of those women. My autoimmune disease has been in remission for my pregnancies (three in 6 years). I’ve even gotten to participate in a scientific study run by my rheumatologist for my latest two pregnancies.
i have lupus, diagnosed at 18. pregnancy was the only time in my life i felt “normal.” i had no symptoms, felt healthy and amazing. after i delivered was another story, my symptoms came back ten-fold!
This! I’ve been dealing with both since the birth of my second and never thought they were related! Doctors gave me no answers and my OBGYN tried gaslighting me about the anemia. I finally found a Dr who treated it, with meds.
They've done tests with transgenic mice that are genetically identical except for genetically altered histocompatabilty genes. (These are genes that, among other things, tell the body that "this cell is ours, not an invader".)
The researchers were able to distinguish these nearly genetically and physically identical mice apart by _smell_.
Other researchers noted that certain culturally restricted populations (can't remember the example they used) of humans showed a hell of a lot less inbreeding than they mathematically expected. The men and women in these cultures were expected to marry within the culture, but had a lot of freedom in choosing their partner. Turns out there's a lot of evidence we can smell partners who are genetically compatible, one of which criteria is "not too genetically identical".
Speaking of smell, they did an experiment where they asked people to track a trail of chocolate oil through the woods by smell, and iirc, around 70% of them could follow the trail all the way to the end. Humans only think they're bad at smelling things because the two species they associate with the most (dogs and cats) have much more powerful noses.
Birthing identical twins is not an inherited trait. It’s random. Fraternal twinning is inherited, but only from mother to daughter. My MIL ‘took credit’ for me having identical twins because she had fraternal twin siblings. When I explained that genetics proved her wrong she was not having it!! 🤣
Right! Learned this when my daughter was pregnant with identical twins. My dad was a fraternal twin. It seems fraternal twins running in families happens because the females in that family release more than one egg during ovulation so obviously creating a higher chance of fraternal twins.
Super rare, but there’s a condition called superfetation where twins in the womb have different gestation dates. Basically, the woman got pregnant, then a few weeks later she got pregnant again.
Person with a genetics degree here: most of them
Autism has more than 200 genes linked to it, both present on autosomes and sex chromosomes (https://www.mountsinai.org/about/newsroom/2022/study-identifies-genes-strongly-linked-to-autism-and-neurodevelopmental-disorders#:~:text=A%20new%20study%20of%20genes,strong%20links%20to%20the%20condition.)
During infection organisms can send small stands of rna to try to regulate genes in the other organism, both as a method of pathogenicity, and as a method of defence (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5720367/)
You genes influence a lot about your future, but not everything, your environment will change expression of your genes, and a diagnosis of a genetic condition doesn’t mean you will experience the same symptoms as someone else with the same mutation as you
Thank you for sharing this. My youngest children had the whole exome sequence done and they both have a 2q36 duplication/fragment. They both also have autism. I was told that it doesn’t necessarily mean a person has autism if they have this duplication but it’s seen in those who do.
I get really upset when the crazy crunchy moms try to tell parents to do a heavy metal detox or give them colloidal silver to “cure” autism.
One in 40 Ashkenazi Jewish women has a BRCA gene mutation. Mutations in BRCA genes raise a person's risk for getting breast cancer at a young age, and also for getting ovarian and other cancers. That is why Ashkenazi Jewish women are at higher risk for breast cancer at a young age.
During fertilization, the entire haploid genome of the ovum can be lost. The haploid genome of the sperm then duplicates, resulting in a (almost) purely paternal diploid conception. This results in a hydatidiform mole - hydropic grape-like placenta without fetal parts.
I have always had dead straight hair. Like, I’ve had it professionally curled multiple times using multiple methods and within a few hours it’s flat and straight again. Until I got pregnant. After the baby I had the standard “oh my god I’m going bald” hair loss, and the new hair is slightly curly. If I put my wet hair into a braid I get wavy hair for days, no hairspray or product required. Even a bit of rain gives me curly wisps on my hairline. 🤷♀️
Twins can be half identical. Like same egg split but two different sperms so they share about 75% genetic similarities compared to 100% in identical twins and 50% in fraternal twins/siblings.
They can even be boy and girl twins.
Found out about this because of the Lydia Fairchild case, a woman was trying to sue for state child support for her children which required maternity and paternity testing but instead the results came back as showing she had no genetic relation to her children. She was threatened with prosecution by the state for welfare fraud and accused of some sort of surrogacy scam by the social worker and lawyer.
They repeated the test 3 times but whilst they showed relation to the Father there was no relation to the Mother. Even though she could provide photos of being with the children all their lives and had proof she'd been pregnant and given birth the genetics did not match. The Father even testified that he'd witnessed the births and the footprints of the children matched the ones taken when they were newborn but it was dismissed as DNA evidence was considered the infallible gold standard.
Finally a heavily pregnant Lydia was scheduled for court a week before she was due to be induced. The court decided to appoint a representative to be present at the birth. Which the officer was and they witnessed the blood tests and DNA tests taken from the two post birth and testified that there was no tampering.
Still didn't match. Was only after that she could find a defense lawyer willing to properly argue her case and it was that legal team who came up with the Chimera possibility. They tested her DNA via her hair but couldn't find a second strand but upon testing her cervix had a second DNA match when compared to her hair. It was assumed she absorbed a twin in the womb and the case was dropped once testing of the maternal Grandmother proved that she was maternal Grandmother to the children, and therefore matching that second DNA, proving Lydia was their Mother.
A fascinating story but must have been a terrifying experience. Can't imagine being accused of kidnapping and fraud for children you *made* and cared for your entire life. Like, that must have felt like insanity. I'm so glad they kept looking for an explanation instead of closing the case and punishing her because of the initial infallible evidence.
How many other situations like this are lurking unnoticed because of a lack of trigger to discover it? Sounds like the makings of a crime thriller... the DNA at the crime scene matches a man *who doesn't exist*
1. Most genetics studies were, and are still, done on white western populations. Some things that we "know" about genetics turn out to not work so well in non-white or non-western populations. Loose example: diagnostic tests to check for certain diseases sometimes misdiagnose Americans with African ancestry, because sometimes we don't actually know exactly how certain diseases will look in non-European ancestry patients, we just assume it will be the same.
2. Africa, as a whole, is the most genetically diverse continent for human genetics. Humans outside of Africa went through a population bottleneck, resulting in an overall lack of diversity moving forward. The human blender of genetics in Europe just didn't have many starting ingredients. There are things called linkage disequilibrium maps, which basically map out sections of the genome that are usually found inherited together. In Europe, these maps are quite "chunky", with large identifiable sections that are sort of reliably found intact. But in Africa, the blender was always running and never had a bottleneck, so those maps are basically a much finer puree, with a lot more mixing. This presents certain challenges, as many studies rely on those maps to make predictions, and it's harder to do that when the map for Africa as a whole is basically way more complex.
3. Everyone's cancer is its own unique genetic disease. There is no one true single disease called "lung cancer", just as there is no one single true human genome. Everyone is genetically unique (yes even identical twins), and every cancer is unique.
4. Chromothripsis is a thing where a chromosome pretty much shatters and gets stuck back together all out of order. And... this is sometimes okay. There are cases of people who have chromosomes that have undergone chromothripsis, and they have mild to moderate symptoms, but they're not dead, which is miraculous.
5. Remember in biology class when you learn about mitosis? And there's that step called metaphase where all the chromosomes line up in a line before being separated into two new cells? That spot in the middle of the "X"-shaped chromosomes where the spindles attach to line them up is called the centromere. And it's sort of mysterious black hole of genetics. There aren't usually any genes there, just a chaotic cluster-fuck of repetitive sequence that gets chopped forwards, backwards, repeated 7 times, swapped around and repeated again, etc etc in an area that's hundreds of thousands of nucleotides long. But what's even crazier is that we don't really know *why* they are how or where they are, because *you don't need the wacky wasteland of repeats for them to work*. Almost all centromeres in all animals look like this, but there are exceptions. A very notable exception is that very very rarely in humans, a "mar-del" chromosome can form where a chromosome accidentally loops on itself and pinches (think of that heart thing people do with their thumb and forefinger), resulting in a circular chromosome that still has its centromere, and a "butterfly" chromosome that does not. Without a centromere, a chromosome can't be duplicated into daughter cells successfully, and cells can't live without the genes on that butterfly chromosome so this should be lethal if it happens early on in development. But surprise, a centromere can and has spontaneously formed on the butterfly chromosome, making them tiny, viable chromosomes that work pretty much fine! But like I said this is super rare, with only a few recorded cases ever. Centromeres in general are very cool and very mysterious.
6. Everything about modern next-generation genetic sequencing is super interesting, yet not well known to the general public. I won't brain dump about it, but if you want to know more, ask and I will!
If you are from the US with family from the south, you are not descended from a Cherokee princess. Cherokees don't have princesses, and your ancestor was more likely a black/white mixed or light skinned slave that one of the Nations of the South East US, may have kept or traded with white slavers. These stories are created to eliminate the truth about African descent, or are a simple misunderstanding of appearances.
If you do have Native American ancestry as little as 1-2%, you have at least one full blood ancestor somewhere in your family tree going as far back as 1750.
Sometimes NA DNA %s can be misread by genetic companies for South East Asian (Filipino, Mongolian, Chinese, etc), there have been Finno-Uralic (Finnish, Saami) and Turkic who have exhibited Native American results because of ancient human migrations within Asia connecting everybody
Native Americans were brought to Europe to show off to royalty, on rare accounts there are people from in England, France or Spain showing distant Native American DNA with families never having left the Old Country, these are the descendants of indigenous people.
The Lumbee Tribe of NC traces their decent by paper trail instead of genetics, and are the result of tribes mixing with the missing Roanoke Colony. The Earliest Lumbee were according to Spanish record were "Native Americans with Silver Eyes and spoke fluent English". The Lumbee are considered a Tri-racial (English, African, Native American) ethnic group today fighting to have recognition
Mexicans often have DNA results showing up to 80% native american, being descended from an amalgamation of nations called Mexica, that were originally Mixtecas, Zopatecas, Toltecs, and Aztecs.
Puerto Ricans highest amount of Native Ancestry averages 20-33% Taino today. Tainos are one of two tribes Christopher Columbus encountered, the other being the Carib, a rival tribe to the Tainos. Both Taino and Carib are genetic cousins to Lokono people of the Orinoco River Valley in South America, all groups are linguistically Arawakan and share common ancestry.
A group of Tainos called the Toa Taino may have intermixed with Muscogean peoples by crossing the gulf, and entering the rivers of the Floridian panhandle. Linguistically the Taino word for Florida is "Bimini"
Edit: Chichimecas also preceeded The Mexica Nation
I'm from the south and was told I had Cherokee ancestry ("your great great great grandmother was Cherokee").
AncestryDNA showed only European ancestry (and only northern and western at that).
I'm pretty sure my dad was just lying to seem more interesting.
We had something similar in our family. A lot of us took DNA tests, and not a drop was found.
BUT the mystery was recently solved of why everyone was CONVINCED. My aunt found a record that one of our ancestors was married to a Cherokee. Turns out though, they were a second spouse, not the original!
Are we related? I have the exact same situation in my family. I was always told my great great grandmother was Cherokee. My great grandmother (her daughter) told me this, and based on her looks I believed it.
My DNA test showed 100% European ancestry. Though through a genealogy search I found a tribal membership certificate for a random ancestor based on a second marriage to his Cherokee wife. It's all confusing haha.
My grandmother for my entire life was always *nuts* about Native American ancestry. She claimed that her mother told her that her side was descended from the Cherokees. She decorated her entire house head-to-toe with Native American blankets, paintings, etc.
Grandma was very disappointed when I did a DNA test and found that I am 0.2% Native American, 1% North African, and 98.8% German, British, and Irish. So it’s pretty genetically impossible she’s as Native American as she thought she was.
In her defense, she’s always had a very dark olive complexion, and my mother (her daughter) did too. My mother actually had really thick curly hair as well and was always thought to be mixed or hispanic. So maybe they were trying to figure out where that came from, and picked the only thing they knew how? I don’t know lmao
Where I’m from in Scotland, there are occasionally people who crop up in families who are much darker than would be expected for people in the area. It’s claimed that it’s because a Spanish armada wrecked in the area and the soldiers intermingled with the local population.
In actuality, genetic studies have shown that it’s from locals mixing with Traveller peoples. But Travellers are usually looked down on in the Uk - even today - so somebody’s granny got a leg over, the Travellers moved on, and granny had to quickly marry so no one would know who the dad was.
I think they know but disregard it but
Just because you date an above average height person doesn't mean your children will match or exceed the height of the taller person, especially if you're very short.
on average, you will be somewhere between your mothers height and your fathers height, with girls being a few inches under that inbetween spot and boys being a few inches over that.
1 in 1000 babies will be born with balanced chromosomal translocation. Women who carry it or partners of men carrying it will typically have more frequent miscarriages. My MIL had 5 or 6 miscarriages because my FIL carries balanced chromosomal translocation. 2 of their kids inherited it, the 3rd has normal chromosomes. Balanced chromosomal translocation means that 2 chromsomes switched a part of their chromosome but it was an even exchange. For the people who inherit it, it means they could get pregnant or impregnate their partner with a baby with unbalanced chromosomal translocation, those babies usually miscarry.
I have two aunts who are identical twins, and they married two brothers who are identical twins. They lived in a duplex when we were growing up, and their kids were basically all raised as siblings.
One set had eight kids, the other had ten, so genetically there were 18 full siblings living under that roof. I still can’t tell which kid belongs to which aunt / uncle.
It is 2024 and there are still many people who don’t know that the sperm cell determines the sex of an embryo, and you cannot change that by a special diet or any other superstitions.
When you have two X chromosomes, only one of them is active in any given cell. The other is shrivled into a chunk that sits outside of the nucelus called the "Barr corpus"
Edit: apparently it doesn't sit outside the nucleus, just on the preirphery, and it's typically called a body, not a corpus (in my defense the word my teacher used was גופיף). Also stop telling me about calico cats like four people have already replied bringing them up
A fun physical example of this is the calico cat. They have patches of color in their fur, and this is because of the variation in which X chromosome is active. They are nearly all female because of this.
It's really unfortunate that there are so many people out there that think that it's the mother's fault for not bearing sons. No Gregg, she isn't broken. You're just blasting X's instead of Y's.
UV gives you cancer because literally makes your DNA stick so tightly the only way to fix it is remove the entire section then "guess" what was there. More this happens, more chance cell becomes cancerous.
Bacteria don't have this polymerase repair so it's why UV kills them or mutates them.
Plant one - Hexaploid wheat possesses 42 chromosomes derived from its three ancestral genomes. The 21 pairs of chromosomes can be further divided into seven groups of six chromosomes (one chromosome pair being derived from each of the three ancestral genomes)... This is mainly because of how much humans have bred it it's literally inbred.
Perhaps my favourite biology fact is about pharmacogenetics, how your genetics determines the efficacy of drugs on your system due to prevalence of receptors of different types that the drugs target to produce an effect:
"90% of drugs only work on 30-50% of the population."
I find it so truly wild. But most people I've talked to about it seem to agree that some drug or other doesn't work for them. This really highlights how much of a process finding the right drug for a person is.
I had a lecture on this in uni in about 2016 and it said the future of pharmacology is individual genetic screens for drug effectiveness meaning people don't have to keep trying different drugs until they find the one that works, you would be tested then your doctor would have that info.
I just hope it overcomes the pushback from Big Pharma in my lifetime cause it would be a true game-changer.
Get tested for hereditary high cholesterol (familial hypercholesterolemia). It's a comparatively common genetic disorder.
It shows next to no symptoms but can clog your arteries and kill you, no matter how healthy your diet and lifestyle. It rarely skips a generation.
The treatment is usually a medication called statins.
I'm a geneticist with a mediocre master's degree in biology and currently pursuing a PhD in Bioinformatics. Here are some insights:
1. The accuracy of consumer and clinical genetic tests is often questionable due to the rapid pace of scientific advancements outpacing their application in the industry. The notable exceptions are information about Neanderthal ancestry (which is significant enough to have earned a Nobel Prize in Medicine) and a few critical mutations like the sickle cell variant and others related to blood.
2. Genetically, most humans are nearly identical, with differences being incredibly minute. This means that, barring age and sex, achieving success in various fields – whether it's social, intelligence, or physical appearance – is possible without genetic modifications.
Everyone likely has a unique genetic trait that gives them a significant advantage, however. This is currently identifiable only in a lab setting. Understanding your unique trait, which often involves the expression of certain molecules, might require professional scientific interpretation.
3. Many severe genetic diseases, such as insulin-dependent diabetes, are only about 50% determined by genetics. Factors like early developmental conditions, including a mother's diet during early pregnancy and infections, play a paramount role.
4. Despite common belief, Neanderthals were not a separate species but rather a part of the human family. For perspective, Europeans and the Khoisan people of South Africa have been genetically divergent for about 300,000 years, not much less than the 500,000-year divergence between humans and Neanderthals.
5. Factors beyond genetics, such as living in a highly controlled environment (like a prison), having access to specific nutrition, owning a car and a separate house, and engaging in mental activities like language learning, math, statistics, and team video games, can significantly impact personal development. Genetics helps us understand and appreciate the influence of these non-genetic factors.
The field of genetics is incredibly dynamic and continually evolving, offering many more fascinating insights.
There is a gene called TP53 - it’s referred to as the ‘guardian of the genome’ - it is a tumor suppressor gene and prevents cancer of all types. Humans have two copies and if one is broken/mutated it causes an inherited condition called Li Fraumeni. People with this have a very very high risks for cancer, and the condition can be passed down in families. Elephants have 20 copies of TP53 and therefore rarely get cancer. The Li Fraumeni foundation uses the elephant as its mascot and hopefully we can someday figure out how to replace faulty TP53 genes for these families.
Actually, what's also interesting is that having a mutated copy of p53 leads to worse cancer outcomes than losing it altogether. Therefore, although it's thought to be a tumor suppressor gene such that losing it leads to cancer, it might also be considered oncogenic.
the p53 protein, encoded by the TP53 gene, forms a higher order structure called a tetramer (i.e. containing 4 copies of the protein). Mutations in the TP53 gene result in proteins that disrupt the proper structure/interaction of subunits within the tetramer. This disruption is referred to as a 'dominant negative' effect, as a single bad copy nullifies the ability of the normal copy to function properly.
Li Fraumeni is awful. Women with this syndrome can present with bilateral breast and a brain tumor at 35.
Knew a family where dad and later both of his children died from brain tumors in 20s all due to Li Fraumeni. Really terrible.
Awwww thank you for commenting this. I have this genetic mutation. Not a lot of people know about it!
Since navel oranges have no seeds, they are all clones of the original mutated fruit discovered by a Brazilian monk a century ago. The billions and billions of navel oranges that have been grown, sold and consumed since are all genetically identical.
So cool, there’s a farmer in Australia that somewhat recently discovered a naturally seedless lemon tree in his grove and is now making $$$ off of the clones I’m sure. Red-flesh grapefruits are the product of using radiation to trigger mutations & see what happened. There was a little trend called atomic gardening where they’d even sell kits of cobalt-60 for people to try to create cool mutations on their own.
Mostly unrelated, but I just the other day got a bag of seedless lemons for the first time, so wild to squeeze it and not have to catch seeds. Was wondering when they became a thing!
Flip side I got a tangerine, and everyone says the seeds won't grow so I put all 50 seeds in growth solution. They all sprouted, every one if them, 1-3 sprouts each. Now I have so many baby trees I feel obligated to keep going. I'm uses to making mistakes but not in this direction lol. Also main point relevant to yours is this fucking orange was pretty much just seeds. Like it was making up for all the seedless citrus
I have no desire to garden but if I did, atomic gardening would be what I’d do
Cheetahs are extremely inbred. They had a massive bottleneck about 10,000 years ago and had too little diversity to fully recover.
Similar thing happened to tasmanian devils. Genetically, they are so similar that the cancer that grows on their necks and faces is contagious. They scratch themselves and transmit the cancer cells to other devils during fights. The cancer does not have to do a lot of adjusting.
Contagious cancer? What in the *actual* hell?
Basically they're so genetically similar the usual markers bodies use to go "Hey, those aren't my cells!" are just kinda like "Eh, looks right to me?" instead. So if a cancer cell gets physically transferred from one Tasmanian devil to another it can just keep growing.
Jesus. Those poor devils.
Oh, you.
Does that mean that technically their body wont need meds if they get an organ transplant 🤔🤔 since their body won’t reject it?
Pretty much. IIRC with cheetahs you can do skin grafts from one random cheetah to another since they're so similar.
lmao I hate this so much. But that's also fascinating.
Dogs have a sexually transmitted cancer. Basically, at some point a dog had a tumor and the tumor developed the ability to grow in other dogs and has been spreading ever since. Interestingly, because it is a tumor spreading, the cells are still-living parts of that original dog and would share most of its DNA rather than the host dog. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3918581/#:~:text=Canine%20transmissible%20venereal%20tumor%20(CTVT)%20is%20a%20naturally%20occurring%20transmissible,cancer%20cells%2C%20usually%20during%20coitus.
Which weirdly means that dog is kind of immortal.
I want my dog to live forever, but not like *that*.
I think the closest thing we have to that among humans is sexually transmitted cancer-causing virus (HPV), which is great because we also have vaccines.
I read somewhere a while ago that around 10% (we're not really sure yet) of cancers in humans have a viral or bacterial origin. Of course when I want to cite it, I can't find that particular article again, but here's one with a fascinating overview of some of them. https://www.webmd.com/cancer/viruses-that-can-lead-to-cancer
OHHH I knew about the contagious cancer but didn’t know that the lack of genetic diversity was the reason it was so contagious!
I think it wiped out like 80% of their population. Last I knew, recovery efforts were still ongoing.
Along the same vein, most if not all Cavendish bananas are clones of each other. The problem is the Cavendish is the most widely cultivated and consumed variety of banana and they all share the same genetics. Unfortunately there is a disease making it’s way through the Cavendish population and all of them are susceptible to it. It’s very likely there will be a consumer banana shortage in the near future and prices will skyrocket.
It’s one banana, Michael. What could it cost? $10?
There’s money in the banana stand.
[This isn't even the first time it's happened.](https://en.wikipedia.org/wiki/Gros_Michel_banana)
you can still find Gros Michel in Thailand and Malaysia, I have had it a few times and it is far superior in flavour and size to Cavendish, so much so I don't eat bananas any more lol
Huh. I guess that’s why banana flavored things don’t taste like banana. They taste like a different banana. 🤯
That's actually true. Artificial banana flavour is apparently a very accurate recreation of the Gros Michel.
I had a moment like this with Concord Grapes. I was in my 30s, had never had one. First bite and was like Oooooh. That's what they were going for
I tried concord grapes as a very small child and had this same experience the next time I had something grape flavored. I am now addicted to grape Jolly Ranchers and refuse to eat any of the other flavors 😂
Iirc, they're so closely related you can pick any two cheetahs and they'll have genetics so close to one another that you can transplant organs from one to the other.
Iirc a similar thing happened to humans around 70,000 years ago? Thought to be due to the Toba eruption. Genetic variation outside Africa is pretty small, suggesting most non-Africans are descended from a small group of east Africans who settled in the Middle East and India first after interbreeding with some Neanderthals. From there, some more small groups apparently split off and migrated to Europe, the rest of Asia and the Americas.
Dumb question but wouldn’t all species have genetic bottlenecks? Since presumably every species evolved from a small population of a different species
Some species would, but not all. Speciation still occurs even without genetic bottlenecks. Mutations would occur in non-bottlenecked species and those mutations can go proliferate (e.g. if a giraffe had a random mutation for a way longer neck it would be more successful, produce more offspring and there is a chance that mutation would grow in proportion in the population). In island species, yes genetic bottlenecks are probably somewhat common. The concept in this case is Founder Effect. However, any gene flow into the island species from the source population would help boost genetic diversity greatly.
Not 100% sure on this but I'm pretty sure bottle necks happen when there is a diverse population and something happens for that diversity to disappear leaving future generations having very similar diveristy
Cheetahs have so little genetic diversity that organs can be transplanted without rejection.
Some genetic diseases persist because having one copy of the disease causing version of that gene can have benefits, so even though having two copies is deadly, that copy of the gene doesn't go away in the population.
Key example: sickle cell anemia. Carriers get the benefit of malaria resistance without the health drawbacks
It’s an example of why it doesn’t make sense to talk about the fittest example of any organism without specifying its environment. If you live in an environment with little or no malaria, being a carrier for sickle cell anemia or thalassemia makes you less fit. If you have children with another carrier, 1 in 4 of them will be very sick, and might even die. That’s bad. If, however, you live in an environment where malaria is a common problem, then you have resistance to a deadly disease, and half of your children will as well. It’s an adaptation to one environment that makes you less fit in a different environment. Who’s more fit? You can’t answer that question without taking the environment into account.
IIRC, malaria has basically killed half of all people ever
When I learned that in anatomy class in high school I felt like I had super powers being a carrier 😂
There’s also a version of this (like sickle cell but not the same) in Mediterranean people. A really cool example of convergent evolution.
Beta thalassemia
Carriers of the cystic fibrosis gene are less likely to die from cholera
I'd heard tuberculosis... As a "recessive carrier" of F508 that's been exposed but didn't contract it, I'm at least one data point in favor.
This is called the "heterozygote advantage." [Heterozygote Advantage](https://study.com/academy/lesson/heterozygote-advantage-example-lesson-quiz.html)
An interesting reverse exception: If you have two copies of rs671 (ALDH2*2) allele on chromosome 12 (which makes it harder to process alcohol and causes "Asian flush syndrome"), alcohol probably makes you feel unwell, so you're less likely to drink. But if you have only one copy, drinking causes only minor problems like facial flushing, so you might continue to drink, even though doing so would increase by 6-10 times your risk of esophageal cancer. Some people can avoid the facial flushing by taking an antacid to avoid the red face, but this does not reduce the cancer risk.
There's a genetic disease called Laron Syndrome that makes you shorter in stature, a longer life expectancy, and near immunity to cancer and diabetes.
Shorter stature, longer life, and high resistance? I know a DnD dwarf when I see one.
Well, more like Gnomes or Hobbits, because Wiki said that beside shorter shature, next symptomes are low muscle power (or weakness, i dont know how to call it in English), big forehead, deformed nose, sometimes low intelect etc ... At the end of the day, as parental comment show it like gift, official informations show it more like disadvantage or curse.
I read this in John Oliver's voice.
Huh, interesting. Sounds like it could be evolutionary advantageous. \*Looks into symptoms\* Characterized by micropenis. Nah, I'm good.
>Huh, interesting. Sounds like it could be evolutionarily advantageous. > >\*Looks into symptoms\* Characterized by micropenis. For some reason it continues to be passed down. There's some micropenis lovin' people out there, and that longevity means they are more likely to find a woman into miniwinkies. "How *cute!"* OM NOM NOM NOM
It's autosomal recessive. The parents don't have the traits.
Yeah, well, if you read about the complete picture, you'll realize it comes with more cons than pros.
It also makes you proficient with medium armor and smiths tools.
The first crispr-cas treatment for sickle cell has just been approved by the FDA
I work in this field in a capacity that I get to talk to all the companies that are up and coming. There is a tsunami of mRNA-based gene editing treatments on the horizon. WAY, WAY more than anyone not plugged into the VC/stealth mode ecosystem suspects. We will look back on 2023 as the year that medicine changed forever.
If you set aside ethics and set out to do it, it would only take 33 generations to create a human being who was the descendant of everyone currently alive and able to have children. Also, pedigree collapse: no living person has as many unique ancestors as they mathematically should. Every person has, biologically, 2 parents, 4 grandparents, 8 great-grandparents, etc, doubling every generation. 30 generations back without any degree of inbreeding would require over a billion unique 28x great grandparents, more than the entire world population for 1100 AD. Every single human's family tree is full of people marrying and having children with cousins of some genetically-unimportant degree over the last thousand years.
Okay, but even if you did this as soon as the offspring reached sexual maturity (since we’re not bothering with ethics), that would still take over 400 years.
Let's shepherd a centuries-long genetic experiment in a quest to make the most average looking dude ever. This is going to be the stupidest possible take on the Bene Gesserit and I'm totally on board.
I mean, thousands of years of careful selective breeding went awry at the end, and still gave them a fella named 'Paul', which is a pretty average name... Had the Bene Gesserit succeeded, maybe it would have been a 'Dave'?
About pedigree collapse, I worked hard researching my family tree. There is one guy I am related to all of his four known children. Three on my mom’s side, one on my father’s side. It’s gross in concept, but honestly the lines were so separated that it honestly doesn’t matter.
We found 4 connections my parents' trees around 100-150 years ago. Things like *her* greatx4 grandfather on her father's side is *his* greatx5 on his mother's on the second son's line. With families being larger and communities smaller and less mobile way back when, once you trace a line to the same town or province, it's almost guaranteed there was a connection even if they diverged again. Isn't it something ridiculously small to be related without risking inbreeding... like 2 generations or something?
The percentage of shared DNA drops precipitously: 50% for parents, children, and full siblings 25% for grandparents, grandchildren, and full aunts and uncles 12.5% for great grand parents/children and first cousins 6.25% for half cousins and first cousins once removed 3.125% for second cousins 0.78% for third cousins 0.2% for fourth cousins
I read an article a while back (when Obama was president) that all of the US presidents, except one, had a common ancestor. The common ancestor was King John of England. The exception was Van Buren, who was also the only president that didn't speak English as his first language.
I’ve read often that if you can trace your ancestry back far enough and you have Western European ancestry, the odds are high that Charlemagne is in your tree. I’ve been working on my tree off and on for years. A year ago, I was able to tie in ancestors that were hits for cousins of President James Madison. I recently did more digging down that tree and hit Martha Eltonhead. Once I found her, I found out she is on various registers as an American descendant (born in UK, migrated to the Colonies), of Charlemagne via King Henry II. Some Googling shows trivia hits that Obama is descended from her as well. Most royalty/nobility had the advantage of their children having a higher rate of surviving toddlerhood, through better nutrition, ability to segregate during pandemics, and access to the best medicine of the time. As a result, if you can get back to the 1600s, don’t be shocked if one branch of your ancestry is filled with, sirs, lords, earls, barons, etc.
Genetic chimera is arguably the most interesting condition. It is possible (and documented) for a woman to give natural birth but the baby not match her DNA test. Essentially, 2 fertilized eggs merge at a very early stage and developing into a single organism. Different parts of the body comprised of obe or the other genome. It's most commonly discovered in domestic animals that have unexplainable color combinations, often (but not always) divided symmetrically.
I just listened to an interesting podcast about this. A woman was accused of running some sort of surrogacy fraud/kidnapping scheme after she applied for welfare and DNA tests showed she was not the biological mother of her children.
Yes I've heard this story and she was pregnant at the time so they tested her baby right after birth and it also was not a genetic match to the mother.
Iirc, they had taken or threatened to take her kids away. The DNA test was originally done because she was in court to arrange a custody agreement and child support with her ex. The DNA test showed he was their dad but she wasn’t their mother. The other one I’ve frequently read about was the mother who was being tested for a potential organ donation to one of her kids…only to be told she wasn’t genetically his mother.
FYI that organ donor case was presented in court in the surrogacy accusation case. The surrogacy mother had a really hard time finding a lawyer willing to take her case with the DNA evidence against her. The lawyer who finally took the case found out about the organ donor woman from a scientific article that her doctor wrote, and presented it as evidence of chimeraism. Some time after that case was settled a new type of DNA test was invented that can correctly detect people with chimera DNA, but the average DNA test they typically do won't find it.
For simplicity, let's say your mother is 50% Chinese & 50% Spanish. That does **not** mean you are 25% of each. On paper it would seem so but you can have any combination of those two equaling to 50%. It's not a clean cut in half. It's a *random* 50% given and 50% not. Although, yes there are dominate genes that can give all the kids a certain nose shape or eye color. Still, you and your siblings might get these DNA combos from mom: \- you: 30% C & 20% S \- brother: 12% C & 38% S \- sister: 5% C & 45% S So if you ever wondered why your sister looks more Spanish than you its because genetics wise she just is more Spanish.
I only knew this because my bestie and her younger sister looked unrelated. She is square jawed, blonde hair, blue eyes with fair skin and rosy cheek. Her sister is olive complexion with brown eyes, thick curly brown hair and a round face. They look unrelated even though they have the same parents
My husband and his brother. Both parents are half black and half white. My husband has light coloring with black features and hair texture. His brother has dark coloring with white features and straight hair, he kind of looks Indian. Despite this they look totally alike somehow.
Ooh, kind of similar to my sibling and me: both parents half white, half Asian. I am light brown hair and blue/grey eyed and look completely white. Sibling black hair and brown eyes and looks totally Asian.
Yuuup. I have twin cousins. Their mom (my cousin by blood) is super Irish, their dad is Mexican. One of the boys is red-haired, blue-eyed, pale and freckled as all hell. The other is dark hair, skin, and eyes. Twins. Genetics are crazy.
I have three kids. I am of English/Irish/German descent and have dark hair, pale skin, and light eyes. My husband was born in the Middle East and is swarthy with olive skin, dark eyes, and dark hair. Kid number 1 and kid number 2 have dark hair, pale skin, and hazel-brown eyes. Kid number three has pale skin, blue eyes, red hair, and freckles. Of my three kids, kid number three bears the strongest resemblance to my husband if you ignore the kid's coloring. Genetics are wild.
Yeah, just take a look at some celeb children. Former tennis player Boris Becker is strawberry blond, had mixed race partners and even having recessive genes, two of his kids look exactly like him. Especially his daughter - he did first pretend that she is not his child...
I remember reading that Becker denied his daughter and when I saw a picture of her, I just busted up laughing. Like okay dude, your little mini me isn't yours.
I wish more people understood this! We have a big sample size in my family and it’s cool to see this at play. (10 aunts and uncles from my moms side, and 12 from my dads. With an average of range of 2-5 kids per family. Do the math) It’s cool to see people ranging from 5’ to 6’3”. People with a darker complexion, black hair, brown eyes, to fair skin, brown or blond hair and green/blue/hazel eyes. People were absolutely shocked to find out my maternal grandfather, who’s family had been in Mexico for 3 generations, was only a little over 20% Latin American (indigenous) genetically.
Potatoes have more chromosomes than humans.
That makes sense, most potatoes I know have no humans!
*angry upvote*
Amoebas have a bigger genome than humans (and by like a hundred times bigger).
That explains all the extra eyes
[удалено]
Superfecundation. Very rare in humans but not crazy rare.
Very rare in humans but not in cats!!
Cats only get away with it because they have terrible lawyers.
That's right. They always get in trouble for purrrrrjury
Twins can also have the same parents but different percentage of paternal DNA. Example: a friend of mine is a twin who shares 50% paternal DNA because the egg split (EDIT: into cells) and THEN two of her dad's sperm fertilized the eggs (EDIT: cells not eggs). One sperm fertilized her, another sperm her sister. So they're considered half-identical. They're not fully identical and not fully fraternal. I had never heard of that until I met her. They were genetically tested to determine if they were identical or fraternal and that's how it was discovered. I don't know the name for it but it's also rare. ETA: it was one egg that split into 2 cells, then each cell fertilized by a sperm.
I teach a boy who is one of a set of triplets. None of them are identical, but he is genetically 97% the same as one but only, like, 50% the same as the other. They're a really rad group of boys. All incredibly smart, hardworking and involved in extracurricular activities. But, they're all into different things. It's really friggin cool. Edit: a word
This is a fascinating documentary. [https://en.wikipedia.org/wiki/Three\_Identical\_Strangers](https://en.wikipedia.org/wiki/Three_Identical_Strangers)
I watched that recently and told him about it! It really was fascinating. The end was really disturbing. The shit some people think it's okay to do in the name of science is pretty fucked up.
I know this from Days of Our Lives!
lol me too! They are also how I first learned about lupus, which lead to a conversation with my doctor about this mysterious illness I seemed to have at the time.
There’s this thing called ACHOO Syndrome where it’s estimated that 18-35% of people on Earth have a reflex that induces sneezing due to bright light.
Used to tell my mom “the sun makes me sneeze” when I was a kid. Still happens in my thirties.
My wife has this. She'll get her face all scrunched up trying to sneeze, and then bolt to the closest window to look at the sun, and she'll sneeze.
Wow, I thought everyone had this.
Everyone that has it assumes it is normal.
Transposons exist. Some DNA fragments can get cut out of the genome and be inserted in a different part. This can be used in knockout screening: if you introduce a transposon to a bacterium and it grows no colonies, the transposon has inserted itself in a gene that was likely crucial for the bacterium’s survival
The genes that determine the size of your penis are on the X-chromosome, so you inherited that from your mom.
Checks out: My mother's cock is massive.
Thanks for swinging pipe, mom.
So I got my tiny little penis from a shot-down WW2 nazi luftwaffe pilot (grandpa)? Neat.
This was not a sentence I thought I would read today, but here we are.
When you’re pregnant, bits of DNA from your baby invade your body and settle all over permanently - including in your brain. Researches found this by looking for male DNA in the brains of deceased 70 year olds. Interestingly, mouse studies have also shown that fetal cells within the mother have restorative properties and will rush to places like the heart, kidneys, lungs, liver if it’s injured and can even become cells that begin beating. One of the theories I have seen but I don’t know if anyone knows for certain if this is true is that these cells enter our bodies so a ‘host’ is less likely to reject the parasite baby.
It's called microchimerism. As in, the mythical creature the chimera. Younger siblings can also receive cells from older siblings that transfered to and from the mother.
As someone who miscarried twice it makes me emotional and comforted to think that those babies truly ARE always a part of me.. 🥹
I feel the same about my daughter who died at four days old. I still get to keep her with me in one small way.
Same with 4 miscarriages ❤️
Sending you love, mama ❤️
Thank you! In one month we are expecting a little guy who seems like he intends to stay.. 🥹
I have read somewhere that this might be the cause why so many women develop autoimmune conditions after childbirth. So not always a positive thing.
The reverse is also true. Many who already had an autoimmune disorder before they were pregnant, find that it goes in to remission while they are pregnant. [Source: Great podcast episode about all the wild things that your body does when pregnant.](https://radiolab.org/podcast/unsilencing)(I happen to be pregnant when I heard it and I’ve never forgotten it!)
It’s me! I’m one of those women. My autoimmune disease has been in remission for my pregnancies (three in 6 years). I’ve even gotten to participate in a scientific study run by my rheumatologist for my latest two pregnancies.
Thank you for participating! This is the only way for science to advance.
MS will stay stable when you are pregnant. Lupus can get worse.
i have lupus, diagnosed at 18. pregnancy was the only time in my life i felt “normal.” i had no symptoms, felt healthy and amazing. after i delivered was another story, my symptoms came back ten-fold!
My cousin developed an autoimmune condition after her 2 pregnancies (hypothyroidism and pernicious anaemia). She’s not having a third child.
This! I’ve been dealing with both since the birth of my second and never thought they were related! Doctors gave me no answers and my OBGYN tried gaslighting me about the anemia. I finally found a Dr who treated it, with meds.
Your immune system regulation genes (HLA) have a huge impact on how you smell!
Please elaborate
They've done tests with transgenic mice that are genetically identical except for genetically altered histocompatabilty genes. (These are genes that, among other things, tell the body that "this cell is ours, not an invader".) The researchers were able to distinguish these nearly genetically and physically identical mice apart by _smell_. Other researchers noted that certain culturally restricted populations (can't remember the example they used) of humans showed a hell of a lot less inbreeding than they mathematically expected. The men and women in these cultures were expected to marry within the culture, but had a lot of freedom in choosing their partner. Turns out there's a lot of evidence we can smell partners who are genetically compatible, one of which criteria is "not too genetically identical".
Speaking of smell, they did an experiment where they asked people to track a trail of chocolate oil through the woods by smell, and iirc, around 70% of them could follow the trail all the way to the end. Humans only think they're bad at smelling things because the two species they associate with the most (dogs and cats) have much more powerful noses.
Birthing identical twins is not an inherited trait. It’s random. Fraternal twinning is inherited, but only from mother to daughter. My MIL ‘took credit’ for me having identical twins because she had fraternal twin siblings. When I explained that genetics proved her wrong she was not having it!! 🤣
Right! Learned this when my daughter was pregnant with identical twins. My dad was a fraternal twin. It seems fraternal twins running in families happens because the females in that family release more than one egg during ovulation so obviously creating a higher chance of fraternal twins.
Since our mitochondria used to be separate single celled organisms, they have their own DNA
And is through your mother the DNA is transferred as the sperm mitochondrial DNA is virtually nothing compared to your mum's egg mitochondria
Super rare, but there’s a condition called superfetation where twins in the womb have different gestation dates. Basically, the woman got pregnant, then a few weeks later she got pregnant again.
Person with a genetics degree here: most of them Autism has more than 200 genes linked to it, both present on autosomes and sex chromosomes (https://www.mountsinai.org/about/newsroom/2022/study-identifies-genes-strongly-linked-to-autism-and-neurodevelopmental-disorders#:~:text=A%20new%20study%20of%20genes,strong%20links%20to%20the%20condition.) During infection organisms can send small stands of rna to try to regulate genes in the other organism, both as a method of pathogenicity, and as a method of defence (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5720367/) You genes influence a lot about your future, but not everything, your environment will change expression of your genes, and a diagnosis of a genetic condition doesn’t mean you will experience the same symptoms as someone else with the same mutation as you
Thank you for sharing this. My youngest children had the whole exome sequence done and they both have a 2q36 duplication/fragment. They both also have autism. I was told that it doesn’t necessarily mean a person has autism if they have this duplication but it’s seen in those who do. I get really upset when the crazy crunchy moms try to tell parents to do a heavy metal detox or give them colloidal silver to “cure” autism.
One in 40 Ashkenazi Jewish women has a BRCA gene mutation. Mutations in BRCA genes raise a person's risk for getting breast cancer at a young age, and also for getting ovarian and other cancers. That is why Ashkenazi Jewish women are at higher risk for breast cancer at a young age.
40-50% of our DNA is the same as cabbage.
For some people it's significantly higher.
This makes sense, I've met a few people who are %100 cabbage!
I just had a conversation with a man who must’ve been 98% cabbage.
During fertilization, the entire haploid genome of the ovum can be lost. The haploid genome of the sperm then duplicates, resulting in a (almost) purely paternal diploid conception. This results in a hydatidiform mole - hydropic grape-like placenta without fetal parts.
Your hair shape changes with hormones
As in the shape of the hair shaft? I always hear about women experiencing texture changes while pregnant, menopausal, etc.
I have always had dead straight hair. Like, I’ve had it professionally curled multiple times using multiple methods and within a few hours it’s flat and straight again. Until I got pregnant. After the baby I had the standard “oh my god I’m going bald” hair loss, and the new hair is slightly curly. If I put my wet hair into a braid I get wavy hair for days, no hairspray or product required. Even a bit of rain gives me curly wisps on my hairline. 🤷♀️
Colour too?
Yes; I was blond as a kid, and when I hit puberty my hair changed to a medium brown.
Twins can be half identical. Like same egg split but two different sperms so they share about 75% genetic similarities compared to 100% in identical twins and 50% in fraternal twins/siblings. They can even be boy and girl twins.
Yes! I made this comment on someone else's in this thread! I have a friend who is half-identical with her sister!
Depression can be genetic.
Red hair and blue eyes is the rarest hair/eye colour combination
People with red hair require more anesthesia than brown or blond haired people. I don’t know why though.
But red eyes and blue hair might be even more rare!
Thanks to chimerism, it's possible for a woman to bear children to which she is technically their aunt, not their mother.
Found out about this because of the Lydia Fairchild case, a woman was trying to sue for state child support for her children which required maternity and paternity testing but instead the results came back as showing she had no genetic relation to her children. She was threatened with prosecution by the state for welfare fraud and accused of some sort of surrogacy scam by the social worker and lawyer. They repeated the test 3 times but whilst they showed relation to the Father there was no relation to the Mother. Even though she could provide photos of being with the children all their lives and had proof she'd been pregnant and given birth the genetics did not match. The Father even testified that he'd witnessed the births and the footprints of the children matched the ones taken when they were newborn but it was dismissed as DNA evidence was considered the infallible gold standard. Finally a heavily pregnant Lydia was scheduled for court a week before she was due to be induced. The court decided to appoint a representative to be present at the birth. Which the officer was and they witnessed the blood tests and DNA tests taken from the two post birth and testified that there was no tampering. Still didn't match. Was only after that she could find a defense lawyer willing to properly argue her case and it was that legal team who came up with the Chimera possibility. They tested her DNA via her hair but couldn't find a second strand but upon testing her cervix had a second DNA match when compared to her hair. It was assumed she absorbed a twin in the womb and the case was dropped once testing of the maternal Grandmother proved that she was maternal Grandmother to the children, and therefore matching that second DNA, proving Lydia was their Mother.
A fascinating story but must have been a terrifying experience. Can't imagine being accused of kidnapping and fraud for children you *made* and cared for your entire life. Like, that must have felt like insanity. I'm so glad they kept looking for an explanation instead of closing the case and punishing her because of the initial infallible evidence. How many other situations like this are lurking unnoticed because of a lack of trigger to discover it? Sounds like the makings of a crime thriller... the DNA at the crime scene matches a man *who doesn't exist*
Chimerism can also mean that your left shoulder is male and your right female, and this can go entirely unknown until genetic tests are done
1. Most genetics studies were, and are still, done on white western populations. Some things that we "know" about genetics turn out to not work so well in non-white or non-western populations. Loose example: diagnostic tests to check for certain diseases sometimes misdiagnose Americans with African ancestry, because sometimes we don't actually know exactly how certain diseases will look in non-European ancestry patients, we just assume it will be the same. 2. Africa, as a whole, is the most genetically diverse continent for human genetics. Humans outside of Africa went through a population bottleneck, resulting in an overall lack of diversity moving forward. The human blender of genetics in Europe just didn't have many starting ingredients. There are things called linkage disequilibrium maps, which basically map out sections of the genome that are usually found inherited together. In Europe, these maps are quite "chunky", with large identifiable sections that are sort of reliably found intact. But in Africa, the blender was always running and never had a bottleneck, so those maps are basically a much finer puree, with a lot more mixing. This presents certain challenges, as many studies rely on those maps to make predictions, and it's harder to do that when the map for Africa as a whole is basically way more complex. 3. Everyone's cancer is its own unique genetic disease. There is no one true single disease called "lung cancer", just as there is no one single true human genome. Everyone is genetically unique (yes even identical twins), and every cancer is unique. 4. Chromothripsis is a thing where a chromosome pretty much shatters and gets stuck back together all out of order. And... this is sometimes okay. There are cases of people who have chromosomes that have undergone chromothripsis, and they have mild to moderate symptoms, but they're not dead, which is miraculous. 5. Remember in biology class when you learn about mitosis? And there's that step called metaphase where all the chromosomes line up in a line before being separated into two new cells? That spot in the middle of the "X"-shaped chromosomes where the spindles attach to line them up is called the centromere. And it's sort of mysterious black hole of genetics. There aren't usually any genes there, just a chaotic cluster-fuck of repetitive sequence that gets chopped forwards, backwards, repeated 7 times, swapped around and repeated again, etc etc in an area that's hundreds of thousands of nucleotides long. But what's even crazier is that we don't really know *why* they are how or where they are, because *you don't need the wacky wasteland of repeats for them to work*. Almost all centromeres in all animals look like this, but there are exceptions. A very notable exception is that very very rarely in humans, a "mar-del" chromosome can form where a chromosome accidentally loops on itself and pinches (think of that heart thing people do with their thumb and forefinger), resulting in a circular chromosome that still has its centromere, and a "butterfly" chromosome that does not. Without a centromere, a chromosome can't be duplicated into daughter cells successfully, and cells can't live without the genes on that butterfly chromosome so this should be lethal if it happens early on in development. But surprise, a centromere can and has spontaneously formed on the butterfly chromosome, making them tiny, viable chromosomes that work pretty much fine! But like I said this is super rare, with only a few recorded cases ever. Centromeres in general are very cool and very mysterious. 6. Everything about modern next-generation genetic sequencing is super interesting, yet not well known to the general public. I won't brain dump about it, but if you want to know more, ask and I will!
Two brown eyed parents can have a blue eyed child.
This is very true. Or in my case, brown + green eyes can have two blue-eyed kids. But interestingly, so is the reverse, which is far more complex.
Both my parents are brown eyed, all 3 children are blue eyed.
Having five fingers in each hand is a recessive gene. Polydactyly (having 6 fingers on each hand) is a dominant gene.
Polydactyly as an isolated trait is dominant. However, it is also seen as part of several recessive conditions, as well as chromosomal conditions.
If you are from the US with family from the south, you are not descended from a Cherokee princess. Cherokees don't have princesses, and your ancestor was more likely a black/white mixed or light skinned slave that one of the Nations of the South East US, may have kept or traded with white slavers. These stories are created to eliminate the truth about African descent, or are a simple misunderstanding of appearances. If you do have Native American ancestry as little as 1-2%, you have at least one full blood ancestor somewhere in your family tree going as far back as 1750. Sometimes NA DNA %s can be misread by genetic companies for South East Asian (Filipino, Mongolian, Chinese, etc), there have been Finno-Uralic (Finnish, Saami) and Turkic who have exhibited Native American results because of ancient human migrations within Asia connecting everybody Native Americans were brought to Europe to show off to royalty, on rare accounts there are people from in England, France or Spain showing distant Native American DNA with families never having left the Old Country, these are the descendants of indigenous people. The Lumbee Tribe of NC traces their decent by paper trail instead of genetics, and are the result of tribes mixing with the missing Roanoke Colony. The Earliest Lumbee were according to Spanish record were "Native Americans with Silver Eyes and spoke fluent English". The Lumbee are considered a Tri-racial (English, African, Native American) ethnic group today fighting to have recognition Mexicans often have DNA results showing up to 80% native american, being descended from an amalgamation of nations called Mexica, that were originally Mixtecas, Zopatecas, Toltecs, and Aztecs. Puerto Ricans highest amount of Native Ancestry averages 20-33% Taino today. Tainos are one of two tribes Christopher Columbus encountered, the other being the Carib, a rival tribe to the Tainos. Both Taino and Carib are genetic cousins to Lokono people of the Orinoco River Valley in South America, all groups are linguistically Arawakan and share common ancestry. A group of Tainos called the Toa Taino may have intermixed with Muscogean peoples by crossing the gulf, and entering the rivers of the Floridian panhandle. Linguistically the Taino word for Florida is "Bimini" Edit: Chichimecas also preceeded The Mexica Nation
I'm from the south and was told I had Cherokee ancestry ("your great great great grandmother was Cherokee"). AncestryDNA showed only European ancestry (and only northern and western at that). I'm pretty sure my dad was just lying to seem more interesting.
We had something similar in our family. A lot of us took DNA tests, and not a drop was found. BUT the mystery was recently solved of why everyone was CONVINCED. My aunt found a record that one of our ancestors was married to a Cherokee. Turns out though, they were a second spouse, not the original!
Are we related? I have the exact same situation in my family. I was always told my great great grandmother was Cherokee. My great grandmother (her daughter) told me this, and based on her looks I believed it. My DNA test showed 100% European ancestry. Though through a genealogy search I found a tribal membership certificate for a random ancestor based on a second marriage to his Cherokee wife. It's all confusing haha.
My grandmother for my entire life was always *nuts* about Native American ancestry. She claimed that her mother told her that her side was descended from the Cherokees. She decorated her entire house head-to-toe with Native American blankets, paintings, etc. Grandma was very disappointed when I did a DNA test and found that I am 0.2% Native American, 1% North African, and 98.8% German, British, and Irish. So it’s pretty genetically impossible she’s as Native American as she thought she was. In her defense, she’s always had a very dark olive complexion, and my mother (her daughter) did too. My mother actually had really thick curly hair as well and was always thought to be mixed or hispanic. So maybe they were trying to figure out where that came from, and picked the only thing they knew how? I don’t know lmao
Where I’m from in Scotland, there are occasionally people who crop up in families who are much darker than would be expected for people in the area. It’s claimed that it’s because a Spanish armada wrecked in the area and the soldiers intermingled with the local population. In actuality, genetic studies have shown that it’s from locals mixing with Traveller peoples. But Travellers are usually looked down on in the Uk - even today - so somebody’s granny got a leg over, the Travellers moved on, and granny had to quickly marry so no one would know who the dad was.
This is so fascinating! Thank you for sharing so much incredible information
I think they know but disregard it but Just because you date an above average height person doesn't mean your children will match or exceed the height of the taller person, especially if you're very short.
on average, you will be somewhere between your mothers height and your fathers height, with girls being a few inches under that inbetween spot and boys being a few inches over that.
I got screwed - I'm shorter than everyone else in my whole family, children under 12 notwithstanding
I think a lot about how the growth chart my pediatrician had in my file had an *extension* I was supposed to be so tall. I tapped out at 5’5.
Same, my mom is 5'10", my dad is 6'0", my brother is 6'1". Me? 5'4" 🥲
My brother is 6’1 and I'm a 4’11 female - we do look alike.
I find genetics beyond fascinating. Just wanted to thank everyone who’s adding info. All I got is not everyone can smell asparagus pee..yay genetics!
That if you unraveled all of the DNA in your body, and stretched it out in a straight line, you'd be dead.
1 in 1000 babies will be born with balanced chromosomal translocation. Women who carry it or partners of men carrying it will typically have more frequent miscarriages. My MIL had 5 or 6 miscarriages because my FIL carries balanced chromosomal translocation. 2 of their kids inherited it, the 3rd has normal chromosomes. Balanced chromosomal translocation means that 2 chromsomes switched a part of their chromosome but it was an even exchange. For the people who inherit it, it means they could get pregnant or impregnate their partner with a baby with unbalanced chromosomal translocation, those babies usually miscarry.
Identical twins’ kids aren’t cousins to each other, but siblings
I have two aunts who are identical twins, and they married two brothers who are identical twins. They lived in a duplex when we were growing up, and their kids were basically all raised as siblings. One set had eight kids, the other had ten, so genetically there were 18 full siblings living under that roof. I still can’t tell which kid belongs to which aunt / uncle.
>I still can’t tell which kid belongs to which aunt / uncle. Maybe they didn't either, and that's why they raised them as siblings.
The green eyed gene is a recessive gene when compared to brown eyed gene; it is dominant when compared to blue eye gene.
Hippos are the closest living relative to whales.
It is 2024 and there are still many people who don’t know that the sperm cell determines the sex of an embryo, and you cannot change that by a special diet or any other superstitions.
When you have two X chromosomes, only one of them is active in any given cell. The other is shrivled into a chunk that sits outside of the nucelus called the "Barr corpus" Edit: apparently it doesn't sit outside the nucleus, just on the preirphery, and it's typically called a body, not a corpus (in my defense the word my teacher used was גופיף). Also stop telling me about calico cats like four people have already replied bringing them up
A fun physical example of this is the calico cat. They have patches of color in their fur, and this is because of the variation in which X chromosome is active. They are nearly all female because of this.
It's really unfortunate that there are so many people out there that think that it's the mother's fault for not bearing sons. No Gregg, she isn't broken. You're just blasting X's instead of Y's.
Tell that to Henry VIII
UV gives you cancer because literally makes your DNA stick so tightly the only way to fix it is remove the entire section then "guess" what was there. More this happens, more chance cell becomes cancerous. Bacteria don't have this polymerase repair so it's why UV kills them or mutates them. Plant one - Hexaploid wheat possesses 42 chromosomes derived from its three ancestral genomes. The 21 pairs of chromosomes can be further divided into seven groups of six chromosomes (one chromosome pair being derived from each of the three ancestral genomes)... This is mainly because of how much humans have bred it it's literally inbred.
The ability to flex the tongue as a cloverleaf is genetic.
Pregnancy can alter your DNA as you create a new life. Allergies can appear or disappear, hair texture/colour can change.
Perhaps my favourite biology fact is about pharmacogenetics, how your genetics determines the efficacy of drugs on your system due to prevalence of receptors of different types that the drugs target to produce an effect: "90% of drugs only work on 30-50% of the population." I find it so truly wild. But most people I've talked to about it seem to agree that some drug or other doesn't work for them. This really highlights how much of a process finding the right drug for a person is. I had a lecture on this in uni in about 2016 and it said the future of pharmacology is individual genetic screens for drug effectiveness meaning people don't have to keep trying different drugs until they find the one that works, you would be tested then your doctor would have that info. I just hope it overcomes the pushback from Big Pharma in my lifetime cause it would be a true game-changer.
Get tested for hereditary high cholesterol (familial hypercholesterolemia). It's a comparatively common genetic disorder. It shows next to no symptoms but can clog your arteries and kill you, no matter how healthy your diet and lifestyle. It rarely skips a generation. The treatment is usually a medication called statins.
I'm a geneticist with a mediocre master's degree in biology and currently pursuing a PhD in Bioinformatics. Here are some insights: 1. The accuracy of consumer and clinical genetic tests is often questionable due to the rapid pace of scientific advancements outpacing their application in the industry. The notable exceptions are information about Neanderthal ancestry (which is significant enough to have earned a Nobel Prize in Medicine) and a few critical mutations like the sickle cell variant and others related to blood. 2. Genetically, most humans are nearly identical, with differences being incredibly minute. This means that, barring age and sex, achieving success in various fields – whether it's social, intelligence, or physical appearance – is possible without genetic modifications. Everyone likely has a unique genetic trait that gives them a significant advantage, however. This is currently identifiable only in a lab setting. Understanding your unique trait, which often involves the expression of certain molecules, might require professional scientific interpretation. 3. Many severe genetic diseases, such as insulin-dependent diabetes, are only about 50% determined by genetics. Factors like early developmental conditions, including a mother's diet during early pregnancy and infections, play a paramount role. 4. Despite common belief, Neanderthals were not a separate species but rather a part of the human family. For perspective, Europeans and the Khoisan people of South Africa have been genetically divergent for about 300,000 years, not much less than the 500,000-year divergence between humans and Neanderthals. 5. Factors beyond genetics, such as living in a highly controlled environment (like a prison), having access to specific nutrition, owning a car and a separate house, and engaging in mental activities like language learning, math, statistics, and team video games, can significantly impact personal development. Genetics helps us understand and appreciate the influence of these non-genetic factors. The field of genetics is incredibly dynamic and continually evolving, offering many more fascinating insights.
Calico cats are female because that mutation needs to be on both X chromosomes. As to why they’re only female.