I can remember my parents borrowing a video version of "where do I come from" and showing it to my brother and myself. He was about 7 and I was about 4. I remember getting bored and walking off.
I think it depends on where your child is at and how they best learn. Also how much they want to know. But the truth is often best, I remember a kid at school whose parents told her a story that suited them, of course she went to school and told the other kids who knew the truth and made fun of him. Poor thing.
Good luck with whatever you decide.

MG