いとこ婚
In-marriage was more frequent in the late pre-Islamic Hijaz than in ancient Egypt. It existed in Medina during Muhammad's time, but at less than today's rates. In Egypt, estimates from the late 19th and early 20th centuries state variously that either 80% of "fellahin" married first cousins or two-thirds married them if they existed. One source from the 1830s states that cousin marriage was less common in Cairo than in other areas. In traditional Syria-Palestina, if a girl had no paternal male cousin (father's brother's son) or he renounced his right to her, the next in line was traditionally the maternal male cousin (mother's brother's son) and then other relatives. Raphael Patai, however, reported that this custom loosened in the years preceding his 1947 study. In ancient Persia, the Achaemenid kings habitually married their cousins and nieces, while between the 1940s and 1970s, the percentage of Iranian cousin marriages increased from 34 to 44%. Cousin marriage among native Middle Eastern Jews is generally far higher than among the European Ashkenazim, who assimilated European marital practices after the diaspora.