Any genealogist who's put off DNA testing because he's confident where his Y chromosome came from might want to reconsider.
Genetics students, reports Steve Olsen, are commonly taught that 5% to 15% of the men on birth certificates aren't the biological parents of their children.
As more people opt to have DNA tests to check for genetic diseases or to explore family history, the more geneticists are discovering false paternity assumptions.
"Any project that has more than 20 or 30 people in it is likely to have an 'oops' in it," says Bennett Greenspan, whose company, Family Tree DNA, traces ancestral links. [Link]