If he inherited his precociousness from his dad, well, then it was only a matter of time. A 15 year-old British kid was conceived using anonymous donor sperm. He submitted his own DNA to a genetic genealogy database, which eventually provided him with several close matches to his Y-chromosome tags. Translation: they all shared the same paternal line (within three generations or so).
The kid searched for someone with the resulting surname [hopefully NOT Gallo. what kind of huge bummer would that be?], who'd been born in a certain place at around a certain time (that much info had been provided to the kid's mother when she got the vial). Bingo. His once-anonymous genetic father was found.
Net net: if you paid for those kegs in college by tossing some seed into the cup, you better keep a few extra chairs handy come Thanksgiving from now on; becuase those kids can track your genes down. Gattaca! Gattaca! Gattaca!
Anonymous sperm donor traced on internet [newscientist.com, via rw]
