Here’s a question. How about someone born overseas, to a mother that is Canadian but her husband is American?
Could the issue be forced, to do a DNA test, to prove that the husband actually is the father?
What if the biological father of the presidential candidate turned out not to be an American?
Great question! Would be really intriguing in the context of a future POTUS election contest.
Anyway, I know the INS now uses DNA testing a lot to prove or disprove that visa applicants claiming close kinship to US citizens are really who they claim to be. It's a big business for some DNA-testing companies.
What's more, the specific issue you raise must have come up, maybe quite a few times.
Still, I have absolutely no idea as to when a DNA test would be required, as opposed to being merely voluntary, especially if the child in question should have a valid birth certificate and/or a valid consular report of birth abroad.
Any immigration lawyers on FR?