I am always amazed at the capabilities of DNA matching. Here's the latest example from an announcement written by Family Tree DNA:
Houston, TX – August 31, 2011 - Family Tree DNA, the pioneer and largest DNA testing company for genealogy purposes, through its Family Finder test, provided the conclusive proof that two National Football League players are half-siblings.
Until a few months ago, Xavier Omon, from the San Francisco 49ers and Ogemdi Nwagbuo from the San Diego Chargers did not have a clue that they were related. Early August, at the request of ESPN, Family Tree DNA performed the Family Finder test on both, and the result was unequivocal: definitely half-siblings. More of the story can be found at the ESPN website, under the “Brother’s Tale” story.