None of us know where our DNA has been. More aptly, we don’t know where it has incidentally traveled to without us. But this does happen, occasionally placing innocent people’s DNA at brutal crime scenes, and adding troubling twists to real-life courtroom cases.
It sounds like the premise of a dramatic thriller movie. And it’s something that forensic scientists are trying to understand better.
In the forensics world, they call this traveling DNA scenario indirect or secondary DNA transfer. Essentially, this occurs when an individual’s DNA spreads to objects and places via other human carriers. Depending on the material where it settles, it can be indirectly transferred as many as six times, according to Cynthia Cale, an independent forensic consultant who specializes in secondary DNA transfer.
