Ew. What?
He’s definitely trying to humblebrag about the fact that he’s had sex before, which is super off-putting. Why else would anyone think to mention their child — a byproduct of sexual interaction — in the middle of a sociology lecture? Who is he trying to impress? Probably not you, but there’s always a chance he has a breeding kink and is trying to gauge the fertility of the crowd. It’s not weird that you’re thinking about this, by the way. Something more inappropriate than thinking about sex during lecture is having the gall to mention a sex-adjacent topic during lecture.