Personally I'm glad they are catching murderers and rapists this way. It's fantastic and as far as we've seen there is no downside when this tool is applied within the context of a state that has rule of law. Even in a totalitarian panopticon like China, it's hard to picture exactly what downside a complete dna database would have. I mean we can contrive scenarios. Maybe a resistance cell is busted while everyone is out and the government is able to deduce the members from dna traces. But it seems far fetched. Even in that scenario, traditional policing techniques are likely to be more effective. I.e. wait until resistance members are present THEN attack the cell. Interrogate prisoners to give up accomplices etc.

Dna identification is pretty cool because the vast majority of cases where it's useful are cases where traces have been left at the scene of the crime or on a victim. That fact, the mere existence of a scene or a victim, constrains the use of the tool mostly to legitimate circumstances.

If my dna were used to lock up a relative who commits a rape or a murder I would be sad but I would consider it justified. I'm not going to do either of those things so I am not worried about whether the police would use dna to identify me. And considering the lack of scenarios where DNA could be misused, this is actually one of those situations where the innocent have nothing or next to nothing to worry about.