Charlemagne had twenty children over the course of his life with eight of his ten known wives or concubines. Genealogists have shown that fourteen presidents of the United States, including George Washington, Ulysses Grant, Franklin and Teddy Roosevelt, and the Bushes are all descendants of the King of France who lived from 2 April 742 AD to 28 January 814 AD.
It is rare indeed that the genealogy of a person of European descent, when traceable, doesn’t hit nobility somewhere. And once it hits one European noble, whether you like it or not, nearly the whole tribe joins your family. Those folks got around.
The reason is simple. First, make a guess how many ancestors you have. It may be a larger number than you thought. Obviously, you have two parents, four grandparents, eight great-grandparents, sixteen great-great-grandparents and so on in a geometric progression. Moving backwards, each generation introduces double the number of ancestors of the previous generation.