>Sex is determined at conception That's only a part of it. Embryonic development plays a part too. >and parents today often know what it is before birth. The

>Sex is determined at conception That's only a part of it. Embryonic development plays a part too. >and parents today often know what it is before birth. They don't know for sure. Not even the doctors can determine it 100%. The estimation is done by looking for a penis with ultrasound. Sometimes the estimation isn't correct and the opposite gender is assigned after.