“Cheetahs Are Extremely Inbred”: 50 Interesting Genetics Facts You May Have Missed At School

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.

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.

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.

That if you unraveled all of the DNA in your body, and stretched it out in a straight line, you'd be dead.

The first crispr-cas treatment for sickle cell has just been approved by the FDA

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.

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.

Having five fingers in each hand is a recessive gene. Polydactyly (having 6 fingers on each hand) is a dominant gene.

Cheetahs are extremely inbred. They had a massive bottleneck about 10,000 years ago and had too little diversity to fully recover.

Your susceptibility to dental cavities. Dental hygiene matters, but genetics plays a huge role, too.

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.

If you see a cat with three colors (black, white, and orange), it's got two x chromosomes.

Cat people tend to know this, but idk about people in general.

The genes that determine the size of your male parts are on the X-chromosome, so you inherited that from your mom.

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.

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.

Hippos are the closest living relative to whales.

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-f**k 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!

not everyone may know is that your genes play a role in determining whether you are more likely to be a morning person or a night owl

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.

Your hair shape changes with hormones