In fact, The Golden State Killer was found by comparing crime scene DNA with the killer's distant cousin's DNA that was found in a public database. Gerald Treece of South Texas College of Law says, “After the Golden State Killer case was solved using technology like this and everybody cheered – I worry about governments getting information on us that they have no business or right to without having a warrant.”
He says you surely sign a very lengthy agreement which could say the company will post its findings in a public database - and who knows who's researching there! Remember – the DNA information and file also have your name and address.
DNA samples and profiles contain private information about health and genetic relationships including paternity and non-paternity. As Treece says, “Things can be exposed because your distant cousin got a DNA testing kit as a birthday present!”