Seriously, how the fuck does a country end up with a 50% inbreeding rate in this day and age? And there's like 3 islamic hellscapes that are that bad or worse while most of them have at least 20x the inbreeding the US does.
In low trust societies, there is an incentive for keeping marriages within the extended family. Islam exacerbates this with its institutionalization and celebration of cosanguinary marriage, even between first cousins. Some have argued that the West was made unique by the church banning all marriages between close relations. It certainly changed the politics because it forced rulers to look further for mates.
Look up the book, The Weirdest People In the World by Joseph Henrich, where weird stands for Western, Educated, Industrialized, Rich and Democratic which gives an insight into how Western civilization differs from the rest.
Review
https://quillette.com/2020/09/08/the-weirdest-people-in-the-world-a-review/
Journal article
Interesting, might have to check the book out.
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