Sending a sample of your DNA through the post may seem like a harmless and novel way of tracing your ancestry, and millions of Americans have already done so, but there is a more sinister side to this relatively new enterprise. If you’re suspected of a crime police can, if they have a warrant, request access to your DNA profile from both the Ancestry and 23andMe websites. The latter has received five requests for customer information from law enforcement, although the company says it didn’t comply with any of these requests.