Your nightmare scenario is so dumb.
What about the government decides they don't like your opposition to fracking and they use your information to poison you with peanut allergy, or give you a pre-disposed diabetes condition that distracts you from your activism.
Or they trace the fact that you are the product of your grandfather's slave raping and just put it out there during an election year.
Or how about they threaten to take one of your children into a mind control program and break them into schizophrenia since they've found out they have a pre-disposition.
Maybe they deploy sensors around town in the future and restrict your movement, mating partner or your career based on your genetics. I could see eugenics coming back around as a 'for the good of the collective, think of the children' idea. Vaccines have, people are forced to have their children vaccinated as if there were no health risks (and I don't mean autism).
How about they develop a genetic virus that kills you and everyone related to you based on your info.
Or they create pre-crime a la minority report based on genetics?
Or you can't afford a lawyer and you get convicted of that case where someone with similar genetics left a partial match.