Why Do Strangers Care So Much And How Do You Respond?

Prefacing this with the fact that I feel incredibly fortunate/lucky that no family member has ever asked when me and my husband of ten years are having children. They know we do not like kids, and they have NEVER brought it up.

But strangers / mutual acquaintances that I meet at work events etc. constantly ask "so do you have kids?" Or "when are you having kids?" And my question is...why do they care so much? I get that they're just trying to make friendly conversation, but it's such an intrusive question. 😵‍💫

So how do y'all respond when a stranger - not a close friend or family member - brings up the topic of reproducing?