Red flag why would he ask this ?

I’ve been on dating apps and so far no luck i met a couple guys i liked but either they’re weird or they responded either late at night/early morning (they might have a girlfriend/wife).

A guy I’m talking to noticed my profile said kids and no longer wanted anymore and he asked how many i had and i responded with 3 and then he asked how many are boys and now I’m wondering why does he care if they’re boys..

I really want to respond to get an answer on why he wants to know how many are boys because that’s weird.

My mind goes straight to something negative but i don’t want to think like that.