At what age do kids normally begin to ask and wonder about creation, if there's a God, and the origins of life and the universe?

I DO NOT mean 'where do babies come from'! I mean, pondering their own existence or purpose and the wonders of the universe, where it all came from.

It's something I've never wondered about in the least and we (adults) don't talk about this subject in our home and it has never been brought up by the children yet.

I don't know if they don't mention it because they've not been influenced at all to think there's a God (we're not religious), or a meaning to life, or if they are just too young. Or both.

I started wondering 'why was I born, why am I here' at a very early age. I wondered what if my father and mother had never met and I had never been born when I was about 7.
I started asking 'what is the purpose of life' when I was about 11 or 12.
This is what my grandfather said about the meaning of life:
'something to do, someone to love, something to look forward to'