After the Age of Oprahfication, people felt free comment on the most private of matters.
Like "are you done"?
Or "How were they conceived"?
Or "I bet my taxes are paying for that."
I plead guilty to having an Oprahfied mentality in my youth: thinking that I could ask and share about anything, without any regard for boundaries.
But now, at a wiser age, I'm here to say: don't.
Especially if you're a stranger. But even if you're not.
If someone wants to volunteer that information, they will.
I know some people are just trying to make small talk. "Hey, you must have your hands full!" (I get that as parents of multiple children, and of autistic children.).
You're better off with something positive and bland. "Oh, aren't they sweet!"