Actress Brooke Shields has a pretty impressive pedigree -- hanging from her family tree 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.
Shields also descends from five popes, a whole mess of early New England settlers, and the royal houses of virtually every European country. She counts Renaissance pundit Niccolo Machiavelli and conquistador Hernando Cortes as ancestors.
What is it about Brooke Shields? Well, nothing special -- at least genealogically.
Even without a documented connection to a notable forebear, experts say, the odds are virtually 100 percent that every person on Earth is descended from one royal personage or another.
"Millions of people have provable descents from medieval monarchs," said Mark Humphrys, a genealogy enthusiast and professor of computer science at Dublin City University in Ireland. "The number of people with unprovable descents must be massive."