If someone blood related enters such a program, certain dna markers get on file that could lead to you. In recent years that way many unidentified dead or serial killers got identified, because someone related made such a test and the fbi database started beeping for a partial match.
It doesn’t matter if you give them information. If your second cousin did, then they can find you.
How does that work? And what if my relationship to my second cousin is not by blood?
See article third paragraph
Not seeing how that answers either of my questions.
If someone blood related enters such a program, certain dna markers get on file that could lead to you. In recent years that way many unidentified dead or serial killers got identified, because someone related made such a test and the fbi database started beeping for a partial match.