I have thought of this possibility if I ever did genetic testing, finding out about different parentage could be shocking. It would be interesting to know about. I also shudder at the fact that it's yet another way for the government to track everyone. Probably almost everyone has enough other people already sequenced that we have almost total coverage already.
His lesson: 23andMe kits are essentially an advanced form of paternity testing.
[0]: https://www.vox.com/2014/9/9/5975653/with-genetic-testing-i-...