Hmmm, well, the Godfather has a daughter of 18, i'm sure we'll find a son of atound 25, so let's say that the GF is around 50. But hey, men can have children up until they die! So I guess it's all up to the mother's age! I'd say that the mother shouldn't have children any later that 50, so if the GF's wife is 55, then the child can be no older than 5. Get what I mean?