Huh: 

The West’s rise can be understood through this lens, as noted by the great anthropologist Sir Jack Goody — a rise sparked by the Catholic church’s ban on cousin marriage. This was introduced in the early Middle Ages, with the ban extending up to sixth cousins by the 11th century. This forced people in England — Angles, Saxons, Jutes, Vikings etc — to marry outside their tribes and thereby dissolved these sectarian affiliations, paving the way for a post-tribal unity. We were the first mongrel nation.