The male and female brain & skeleton (the pelvic girdle is used to establish the gender of human remains) are markedly different. There's no changing that. One can only impersonate the opposing gender with the aid of surgery and daily jabs of synthetic hormones. Doctors who ingratiate a patient's self-loathing tendencies through radical means (mutilation & blood-intoxicants) violate their sacred Hippocratic Oath: "Physician do no harm."