This is a very touchy subject.
It is common in the Arab world to marry cousins, sometimes first cousins. This is part of creating and maintaining a tight intimate family structure.
There is a genetic component to the issue of consanguinity. It leads to biological defects in the offspring. This genetic defect consequence is important in many fields. It determines the minimum size of any animal population that can survive. It is also the source of tribal warfare as a way to get brides from tribes of different gene pools. African slavery was also good for the gene pools of Africa.
Too many defects, reproduced too often and the population dies out. For humans, we don’t know this minimum population size.
For Arabs this presents a different issue than it might for a population in a prosperous developed society. In an Arab village there are many jobs, occupations and functions that can be performed by a developmentally disabled child. Feeding animals, herding, roof maintenance are just a few. In urban Arab areas it is more of a problem.
In Palestinian society a mentally retarded child can be groomed as a suicide bomber. This is often the case. Not a satisfactory solution to the problem as seen by modern Westerners.
Such young people are being used extensively in Daesh confrontations in Iraq and Syria. This article shows the high correlation between successful Daesh recruiting and the rural Arab areas, where consanguinity is high.
The whole issue of Arab consanguinity and assimilation to the modern world is one that will have to be discussed someday.