>>3316331 (OP)Generations of inbreeding. In Islam marrying your cousin is encouraged, firstly because the prophet married one of his cousins, and you have to take him as example. Secondly because muslims have endogamous clanic family structures. For jews it's because they lived in small communities and couldn't marry goyim.
Inbreding also happened Ireland, this is why most of them look deformed too.