That might be a standard followup question? Cuz once my gyno or her nurse asked me the same thing (but i was in my 40's), and as I started to explain (snowball's chance in hell), she interrupted after the first few words and said, "that's okay, just checking, but you'd be surprised what some people DON'T know" or something like that. So they're just trying to protect someone's unborn child who can't protect itself yet. Start a therapy fund for THAT kid!