DNA Truthers

Kit Eaton surveys the science:

In Osama's case, the DNA tests don't necessarily involve a reference sample from the man himself (presumably because it's hard to find), but reportedly from his sister who died in Boston recently. Tissue from her body was used to create an extensive reference DNA fingerprint. Because your parents give you some of their DNA, they also give your siblings some of the same genetic code–which is why sibling DNA tests work. …

But here's the thing: DNA matching isn't an exact science, and sibling matching is slightly more inexact. It all comes down to a probability, with a statement like "there's a one in one quadrillion chance this isn't the same person in both DNA samples." In other words: conspiracy theorists still have something to talk about.