Europe, at least any part that was under Catholic influence for a few centuries is a massive outlier in its low rates of consanguineous marriage.
They might not marry close relatives (say, those with common ancestors from 200 years ago), but when it’s customary to only marry people from your own town with a population of 1000, this means that lots of your ancestors from 500 years ago are your spouse’s ancestors too, so you still share lots of genes.
Urbanization in the 19th and 20th century mean this is very seldom still the case. How many people live in such small towns? And those who more often find spouses via work or in the course of their education, which seldom takes place in such small towns.
In any case the defect rates for such towns are only very seldom a problem. A better point in your favour might be the relative close relatedness of say the Aksenazi Jews.
They might not marry close relatives (say, those with common ancestors from 200 years ago), but when it’s customary to only marry people from your own town with a population of 1000, this means that lots of your ancestors from 500 years ago are your spouse’s ancestors too, so you still share lots of genes.
Urbanization in the 19th and 20th century mean this is very seldom still the case. How many people live in such small towns? And those who more often find spouses via work or in the course of their education, which seldom takes place in such small towns.
In any case the defect rates for such towns are only very seldom a problem. A better point in your favour might be the relative close relatedness of say the Aksenazi Jews.