As a child, I heard some rumours about where babies come from.
I won't bother to make enquiries here about their veracity though.

I would say here (Mudcat) was the perfect place to make such enquiries, Keith, and an ideal place to bring up any old rumours or fairytales. They are, after all, part of folklore and to find out how and when they started should be part of the folklorists studies. In fact, I will start a thread forthwith.