@JeanP #134723
Oddly, the X or Y chromosome only determines the genetic sex. What determines if the pre-developed organs making up penis/protate/testicles or vagina/uterus/ovaries is in fact factors not even tightly connected with either sex chromosome, to respond to a bath of androgen chemicals that the fetus is washed in within the uterus. So far, Andrew is right!
Where he’s wrong is, the hormones the mother takes have little to do with it, and at the point the hormones she takes have an impact, the fetus is in dire danger, and quite likely so is the mother. I haven’t found direct information, but from what I’ve gathered the sensitivity to those androgen hormones, which determines how the genitals develop from there, is tied in with genes that are not on either the X or Y chromosome. And because of this, it is possible to have androgen sensitive genetic females (XX forming a penis) and androgen insensitive males (XY forming a vagina).
This is only one of the many ways in which in utero sexual development is so much more complicated than the Kindergarten Cop definition of boys and girls.