"You don't look 36 though" — why CF often look younger

This was said to me twice during the same day. I'm not a particularly handsome guy or anything, but I guess I do look younger, maybe around 30. We were discussing ages with coworkers and pointed out that our boss, who is in early 40s, also looks much younger.

Then I realized what we all have in common: we have no children. On the other hand, I remember a former coworker who wasn't much older than me, but already had a face full of wrinkles and constant bags under eyes. He has raised three daughters.