And if they didn't ?
I've been not answering this bilge for 40 years. Try and get an answer out of me by abusing social convention and see how much it hurts.
But I can see an 18 year old first interviewee feeling under pressure to provide an answer. And I will say here and now I don't think that is right.
What happens if the candidate just Makes Shit Up ? "My Dad was a Brigadier General and my Mum a milkmaid". Would they make you prove it ?
A: But what about you and Mum?
H: Well yes, yes, I grant thee when I first met her I was the farmer's
son and she was just the lass who ate the dung, but that was an
exception.
A: And Aunty Dot and Uncle Ted.
H: Yes, yes alright, he was a pig poker and she was the Duchess of
Argyle, but-
A: And Aunty Ruth and Uncle Isiah, she was a milkmaid and he was-
H: The Pope! Yes, yes, all right. Don't argue. Suffice it to say if you
marry we need never be poor or hungry again. Sir, we accept.