Comment on Why does incest result in birth defects?
where_am_i@sh.itjust.works 4 months agoWhen combining two genetic codes you don’t have a way of predicting and selecting what’s good and what’s bad.
Similarly to doing a homework, if you got two copies from two different people and their solutions are not aligned it could mean that one of them is right, or they’re both wrong, or they’re both right, cuz there can be multiple ways to solve a problem, even a math one. You need to be able to circle back and discuss solutions with both of them to understand which one is correct. You do not have this mechanism for genetic cross-over.
Coincidentally, two people can be wrong about something together. School assignments were notorious for setting up traps that everyone would fall for.
TL;DR comparing answers and picking “only matching answers” doesn’t seem like a necessarily better path.
Nemo@midwest.social 4 months ago
I explained that in the second paragraph. You get genetic defects even without inbreeding, sure, and you get wrong answers on homework. But you’re more likely to catch wrong answers if two people worked independently, and you’re more likely to have a healthy set of dominant traits when people marry outside their community.
To reiterate: Inbreeding allows for greater expression of recessive traits. Recessive traits are more likely to be disadvantageous than dominant ones, because dominant traits that pose disadvantages are winnowed out by natural selection, whereas recessive ones can be carried unexpressed and passed to the next generation.
A good example is cystic fibrosis. We found out my wife is a carrier. If I was also a carrier, there’s the risk a child could have cystic fibrosis, which would prevent them from surviving long enough to reproduce. But since I’m not, there’s merely the concern that she passed on the carrier gene to our children. It doesn’t affect their survivability at all, and they will live to be the chance to pass on the recessive carrier gene themselves.