Stanleys, Crews, & Hesters I recognize as all being Quaker Families. The Quaker Faith frowned on and shunned members for "marrying out". This led to limited choices for marriage age matches, and a lot of cousins marrying cousins. Several times in my tree sets of 2 or 3 siblings would all marry children of the same neighboring family group. Then their's my wife's grandparents that never even realized they were 2nd cousins. So yea, happens a lot. The rarity is the tree with NO collapse.