In spite of what most people believe there is no straight line between chromosomes, genitalia, sex and gender identity.
Did you know that one in 20000 people assigned male at birth have two XX chromosomes, or that as many as one in 1000 male bodied persons have an XXY configuration? There are many women with an XY combination, as well.
You probably know quite a few men and women already who do not live up to the simplistic ideas of sex and chromosomes, but you do not know it. They may not even be aware of this themselves.
Have you ever had your own DNA tested?
Read my blog post on Genes, hormones, sex and gender identity