For what it's worth, I come from a county settled in the 1820s and descend from quite a few of the early-settler families. There's another person who does the same. Without any "cousin marriages" having taken place (my grandmother's brother married my grandfather's cousin, but the two of them weren't related to each other), on the various lines we're 2nd cousins, 4th cousins twice, 5th cousins, and 7th cousins, with various degrees of generational "removals" included in those. It would appear that these multiple lines of common descent piled on each other make us more closely related genetically than we are genealogically.

Has anyone else found an instance of this?