The problem has been noted but blissfully ignored. Not only problems of 700 years of inbreeding, but women are held in such poor esteem I image prenatal care is abysmal if any exists.
http://www.as.wvu.edu/~kgarbutt/QuantGen/Gen535Papers2/Inbreeding.htm
Recalling that video posted a day or two ago of that Islamist murdering his wife while others stood by watching.. I recall also that there is one advantage for the daughter marrying a close relative. That is, there is less likelihood of her being beaten beyond recognition, tortured, or even murdered.