In tracing a 'side branch' of the family tree, I found two sisters and their brother who married two brothers and their sister. So far, not so unusual, I suppose: I presumed that the families became close after the first of these weddings (in 1909 in Brentford; the other two were in 1918, in Acton Green and Brentford). However, subsequent research showed that they were all first cousins!
I know that first cousin marriages were not uncommon, but would 3 such marriages be especially unusual? I'd appreciate any comments.
(I've checked most of these findings, so I'm pretty sure I'm right).