I recently got an email from a (distant) cousin trying to identify his biological grandfather, as his father was adopted. With a few tricks and some math I was able to narrow it down to one of two brothers who attended his grandmother's high school. Genealogy is fun, and DNA makes it more fun.... really cool to uncover those 100-year-old affairs that your ancestors thought they got away with.

Anyway, DNA stands for Deoxyribonucleic Acid.
Or maybe it doesn't. You know what to do.