The Genetic Genealogist has been discussing how DNA testing, particularly of the Y-chromosome, can tell men their surname. He refers to research from Mark Jobling's lab at the University of Leicester that says two men who share the same surname have a 24 percent chance of sharing a common ancestor; that chance increases if the last name is rare. In a related post, he links to a BBC article that says that male adoptees are using genetic genealogy databases for just that reason. Larry Moran says this is an ethical problem since the wishes of the two parties, adoptee and biological father, are at odds. Furthermore, testing could also reveal who is not that person's father.