Guide to dating your cousin
I think this explains the patterns in the United States, extremely isolated communities are more inbred, while most Americans have traditionally been very mobile and not relied excessively on family networks.
In northern Europe cousin marriage was not unknown in the 19th century, Charles Darwin famously married his cousin.
If I told you than the chance of first cousins having children with a birth defect is 4-7%, vs.
3-4% for a non-consanguineous couple, it might not sound that bad.
In less individualistic societies where zero sum power dynamics are still operative it may also be beneficial for a wife to be related to the family into which she is marrying.
Anthropologists in South Asia attribute the more equitable power dynamics between the genders in Hindu South India as opposed to more patriarchal Hindu North India to the fact that in the South cousin (and uncle-niece) marriage is practiced, while in the north exogamy is the norm.
That’s why most first cousin marriages don’t produce children who are monsters.Why is it that cousins have a higher risk of this occurring?Because two cousins are much more likely than two random individuals to share the same distinct gene from a common ancestor, because their common ancestors are so much more recent.The pagan emperor Claudius married his niece Agrippina the Younger, while the Christian emperor Heraclius married his niece Martina.