My son is 8 and has no interest and quite happily thinks babies come when a mum and dad love each other... but not all are lucky and so not all have babies. I think I must have told him this at 4 and he has never questioned it since.
However at what age did you have the talk about how babies are made with your child? And what level of detail? It's only come up for me as a friend told me her son (also 8) had asked and so she was straight up with him. Fair enough, but now I know it will be discussed in the school yard I want to prepare my ds!
To be honest I'm a bit sad. Seems like a loss of innocence to tell him :(