Who is Frances Culpeper from Albion's Seed: Four British Folkways in America and what is their importance?

Frances Culpeper turned out to be of great import due to the whole idea of "cousinage." "Cousinage" was the intentional interweaving of families within a particular region. The relations were distant enough to avoid all or most of the genetic disadvantages of inbreeding but close enough so that, especially amongst the highest social classes, a set of families would all be related to one another.