There’s a reason interviewers in the US won’t (or shouldn’t) even ask if the candidate has a spouse. If they ask something about that specifically, and the answer indicates some kind of protected status (a man says “my husband” or reveal which place of worship they got married in) and they then decline the candidate, the candidate could make the claim they were denied because they’re gay or practice whatever religion or something else.

Asking personal questions could be seen as a way to elicit information about a protected status and thus give a rejected candidate ammunition for a claim, whether warranted or not.

It’s best to just keep questions focused on the workplace.