I just saw this map http://consang.net/images/c/c4/Globalcolourlarge.jpg (available on Archive.org if it would ever disappear) and become curious about how inbred people actually are.
In quite a few countries around 25 % of all marriages are between cousins. If that number is constant over the generations, how inbred is the average person living in such a country?
In the worst countries around 50 % of all marriages are between cousins. Same question as in (1).
And the same the question for the countries with only 1 % cousin marriages.
Where do these three scenarios converge? Naïvely I figured it should be at 50 %, 100 % and 2 % but I can’t really motivate that guess.