It's unlikely to happen because what you said is mostly BS. A smart phone contains all kinds of sensitive information like logs of where you've been and of private conversations between you and several other people (which may or may not be related to a case the police are investigating). Your DNA can't possibly contain information like that. Today it might be able to tell the police you have blonde hair and blue eyes, but so can your driver's license. Sure it might eventually be able to let the police generate a picture of what you look like based on your DNA, but once again so can your driver's license. It might even be able to tell the police whether you have a small penis (or something along those lines), but I'm pretty sure they won't be able to use information like that against you in court.
It really is no different than collecting fingerprints at a crime scene, semen from a rape victim, etc.