The criminal tracing thing - they’ve already caught criminals who never did a DNA test. A couple relatives had taken a test, some crime scene DNA was similar, they contact the relatives and interpolate who it was and bang! Got the guy.

At this point, they have so much DNA data I bet they can tell what everyone’s background is, whether you’ve taken the test or not. I guess if you don’t know your actual parents - adopted, bastard children etc, you might have some level of genetic anonymity.