" Girls are drawn to the many behaviours females exhibit (i.e. primping and preening, mothering, a strong desire/ability to express themselves verbally)."

There's considerable evidence that those behaviours are as much learned as ingrained at birth. Boys wear blue girls wear pink so of thing. Take away that sort of social conditioning and certainly in pre puberty children there is little that separates their behaviours. How fast they can run, physical strength has more to do with size that gender.

If there is a gene, something in our stem cells that draws us to our behaviour, something akin to what makes someone gay then it puts a whole new facet to the debate about Trans people. It makes abig hole in the, "there are only two genders" claim.