I didn't find anyone who described a real cause for intersexuality, although about half of the woman (XX chromosome) also suffer from Congenital Adrenal Hyperplasia (CAH), a genetic disorder that messes with the production of sex hormones and may cause intersex.
I agree, Jeanne, that it's sad that she can't reproduce. Even sadder was the traditional cure ... removing the unusually large clitoris in childhood thereby rendering her relatively unresponsive to physical sexual stimulation for life.
Carl.