Additionally, your hypothetical also assumes that the person(s) related to the supposed subject have their DNA on file or are somehow compelled to provide it as evidence - precluding some kind of existing database, or a kind of chicken|egg situation. That is out of scope of this argument.
That is actually a very safe assumption.
As articles like http://www.pbs.org/wgbh/nova/next/body/dna-databases/ make clear, police already ARE creating DNA databases. And since there is little regulation around this right now, they are free to be creative in assembling them. For example you can get a good DNA sample from the straw used to blow into a breathalyzer. So get stopped at a routine traffic stop, your name, license plate, and DNA can go into a database. And voila, police can now match you and your relatives against crime scenes!
As technology improves and costs come down, incentives to match everyone to DNA tests will go up, not down. Heck, I remember as a child in Canada over 30 years ago having police come to my elementary school and taking everyone's fingerprints. I believe that the cause was so that if anyone went missing, they could identify us. But once that data is collected and goes into databases, it doesn't come out.
Heck, how many parents would give consent today for their 2nd graders to get a DNA test for that purpose?
That is actually a very safe assumption.
As articles like http://www.pbs.org/wgbh/nova/next/body/dna-databases/ make clear, police already ARE creating DNA databases. And since there is little regulation around this right now, they are free to be creative in assembling them. For example you can get a good DNA sample from the straw used to blow into a breathalyzer. So get stopped at a routine traffic stop, your name, license plate, and DNA can go into a database. And voila, police can now match you and your relatives against crime scenes!
Think this is crazy? This has already been happening. See https://www.prisonlegalnews.org/news/2013/aug/15/maryland-co... for breathalyzer DNA being used to convict of a crime, http://edition.cnn.com/2013/02/26/justice/supreme-court-dna/ for the Supreme Court OKing DNA tests for arrests without a conviction, and http://www.nbcdfw.com/news/local/North-Texas-Drivers-Stopped... for a random example where this was done to random people at a traffic stop. Yes, there is outrage at present. But over time this could become the new normal.
As technology improves and costs come down, incentives to match everyone to DNA tests will go up, not down. Heck, I remember as a child in Canada over 30 years ago having police come to my elementary school and taking everyone's fingerprints. I believe that the cause was so that if anyone went missing, they could identify us. But once that data is collected and goes into databases, it doesn't come out.
Heck, how many parents would give consent today for their 2nd graders to get a DNA test for that purpose?