Brant, some areas of biology are more complicated than flip one-liners ... I think you do well understand that there is variation in genitals. I have explained this before at length here. Please review the 'spectrum' of real-world and recurring cases of babies born with indeterminate external genitalia. It is relevant and not all that complicated in principle: the X and the Y have jobs to do as chromosomes. In a normally developing fetus, their job is done to the norm. It is the not norm I think we are concerned with. You cannot norm an XXY 'girl' pre-puberty. The chromosomal 'sex' type does