Why is cousin marriage especially common in Muslim-majority countries?
Andrey Korotayev and Duman Bahrami-Rad hypothesise that Islamic inheritance rights for daughters motivated cousin marriage, to maintain family wealth.
This Substack considers several alternative explanations:
Pre-Islamic bride price and property rights
Quranic inheritance rights for daughters and widows
Arabisation
Clan pride
Institutions
Cultural assimilation (versus geographical isolation)