When I was working recently, I was asked frequently about my marital status. Do I have kids. How old was the oldest person I had sex with? NTs just ask, and then you're on the spot.
You don't have to answer though. And "do you have kids" is a pretty normal question but "how old was the oldest person you had sex with" is not something normal people ask other people during a lunch break or something. If someone asked me that I would say what's wrong with you, asking people such personal questions, go bother someone else.