When does the gender of the baby get decided?

The baby's characteristics, gender included, are determined at birth. I stumbled upon this in a play through where the father was bitten and turned into a vampire after conception, but before birth. The child was born a vampire -- something that should have not occurred if this was not the case. And so, at the moment of birth the game randomizes characteristics from the two parents at that time, not at conception. It will evidently also take into consideration the foods eaten and music listened to in determining gender probability at that time as well. This makes sense, as it seems to utilize the three day period between conception and birth as a running counter to skew statistical probability and then does its calculating at the end.

EDIT -- Nuts. This thread is from last year. I already replied to it. Well, there it is.