Here's an interesting article from the Associated Press that says that almost everyone descends from a famous ancestor. In our family, that could be the Kovno Rav. The article goes into detail about actress Brooke Shields' pedigree. Among her ancestors are Catherine de Medici and Lucrezia Borgia, Charlemagne and El Cid, William the Conqueror and King Harold II, vanquished by William at the Battle of Hastings.
Even more surprising, according to Irish computer scientist and genealogy enthusiast, Muhammad, the founder of Islam, appears on the family tree of every person in the Western world. Who knew?