Why Inbreeding is Terrible AND Amazing - Bret Weinstein | After Skool

I'm curious to know why inbreeding leads to such poor offspring.

Well, it does.

And it doesn't, I think this story has been asymmetrically propagated.

Let me tell you why it causes problems.

And then let me tell you the other side of the story.

We are diploid creatures, meaning that we have two copies of all of our genes.

Genes differ in the parameter called dominance.

So there's some genes that you can have two different copies, and if you have one copy, that's what affects the phenotype.

So eye color would be this sort of thing.

I happen to know that I have a blue-eyed gene that I got from my mom and a brown-eyed gene that I got from my dad.

How do I know that? I know that because my mom has blue eyes.

In order to have blue eyes, you have to have two copies of the blue-eyed gene, which means that when she had me, she had no choice but to pass one of those on.

So I got a blue-eyed gene, and my eyes are brown, which means I also got a brown-eyed gene, so I'm heterozygous.

And the blue-eyed gene is hidden completely.

It is a

recessive.

There are many instances in which a recessive gene is bad, often devastatingly so.

And the reason for that is because one of the ways that a gene becomes recessive is when you take a functional gene and you break it.

And you get a mutation that takes a gene that successfully produces a protein and the code gets changed and suddenly that protein doesn't work.

Now, it's recessive because you have a good copy of the gene, and maybe that gene actually has a regulatory apparatus that detects how much of the product you need, and it keeps producing from that functional gene more product until you get to the point that you don't need more, in which case you won't see the broken gene because the non-broken allele will be working overtime.

You feel the same.

So the important thing, though, is because there are many of these broken genes that are recessive, they circulate because there's no downside to having one.

There's a downside to having two.

But if you only have one, you're not paying a cost or at least not a substantial one.

So the estimate is that each of us is walking around with something like eight on average devastating recessive alleles somewhere in our genome and that we don't know anything about it because we have a functional copy of the gene in question and we live our lives blissfully unaware.