Gromky: One primary thing is inbreeding really isn’t as risky as most people think. You don’t instantly get flipper babies, and marrying cousins was the norm in Western civilizations forever. One of the best ways to keep your money/land/wealth in the family was the classic “keeping it in the family,” rather than paying a dowry to some random stranger.
The biggest risk with inbreeding is that it reinforces rare negative genetic traits and makes it much more likely that rare recessive traits will show up, because both parents share it. See hemophilia in the English royal family. So if there isn’t a predisposition towards something like that within a population, it’s hard to see the negative effects. Also, many of those small islands had some level of travel or movement between them. That was how people got on the islands to begin with. A couple people stupid/crazy/desperate enough to take off in a boat and end up somewhere else.
satanicpuppy: They don’t have to. In small populations, bad recessives drop out very quickly, because they become expressed very quickly…If you have a nasty genetic disease, it won’t lie dormant, it will kill people. After the bad recessives drop out, everything stabilizes, and the population can continue until some disease that no one has a resistance to kills everyone in a week.
Inbreeding leaves you with a lack of genetic diversity, but that’s only bad if something is around to take advantage of it. Otherwise, as long as you’re not getting a bunch of nasty mutations or weird immigrants with lots of genetic problems, you don’t need a very diverse population.
OnkelFax: Inbreeding is also an efficient way to expose deleterious mutations and subsequently get rid of them. In addition, already a little amount of gene flow (outbreeding) can fix a lot of inbreeding. But then again, there are several examples of inbred populations that carry traits that confer problems. But as long as there are no competitors (you are isolated!) it may not matter.
martinborgen: They don’t.
These places typically do have higher risks of inherited genetic diseases. That said, inbreeding isn’t instant madness, just a higher risk.
SirLenzalot: I can answer the modern times one!
Iceland has a dating app that lets you know if your prospective date is your relative.
skybrocker: There is an app for Icelandic people to make sure they aren’t related: https://www.google.com/amp/www.cbc.ca/amp/1.1390256
Haha warning 🚨 alarm!
pitathegreat: Not just a concern for island nations. Google Hapsburg chin. If ever there was a spokesmodel for genetic diversity…
Then there are the blue skinned people of Kentucky.
VirtualMoneyLover: Well, they don’t. certain Amish communities needed to be introduced to other, 200 miles away communities because the genetic inbreeding was too much.
jonesjr29: There used to be an island in the Bahamas called (I can’t remember) It was the only Island comprised solely of white people; Black bahamians were not allowed on the island after 6 p.m.As a result, there was a lot of inbreeding which was evident during visits we made to the island, ostensibly to tour the island, but really we went to look at all the mentally and physically handicapable people. I believe this genetic isolation of the island has changed.
iamthechiefhound: Are you curious because of Shameless?
The way the paint spreads
skeptical_remark: I want to see the final product!
pikameta: Happy little trees!
UnlivingBug: Fun fact: this is called mocha diffusion. Its a type of slip that people put on pottery and then when you add color it makes this pattern! Theres several ceramicists who make videos of this process quite often
relish-tranya: Gotta be some fractal math in there