Police are never 100% certain or 100% right, that's why we have all these rules about 'em.

For better or worse, we have a DNA database. The law decided that if you were convicted (or just arrested) you could be forced to hand a sample over and be put in the database. There was quite a bit of argument over that, and while it would be nice to re-argue it, that's not happening right now.

We did not decide we were putting your whole family in the database. Now we are learning this is a consequence. (And since the black population is over-represented among those convicted and arrested, it means we end up with a large proportion of black people "in" the database compared to whites or other groups.)

You seem to be saying, "We accepted a database of felons, so now you might as well accept a database of everybody because if now flows from a database of felons." But we didn't accept a database of everybody.

Note that we *could* design the databases to only return exact matches. There are hashing techniques that should be able to do that.