Nephew, cousin, and SIL all at the same time?
Nephew, cousin, and Son In Law all at the same time?
Yes, welcome to the wacky world of Islam, where marrying a cousin is considered normal, and in some places (like Afghanistan) is the majority of marriages. Birth defects are rampant after generations of such inbreeding. The insular Amish suffer high rates of birth defects too.
The example of the Prophet is held so highly in Islamic law, that incest practiced in his backwater, at that time far back in their development, has been enshrined as a revered social custom.
The rate of birth defects is 2-3% higher when first cousins marry, but when this is done for generations, the rate gets to around 25%. Saudia Arabia has a lot of family members who are kept inside the walls of the family compound.
It is pretty common that mentally impaired folks are used for the suicide attacks that have become popular within Islam since Ayatollah Khomeni reintroduced them - they can be remotely detonated, by someone who is not quite a moron themselves.