At present, the major difference between transgender and intersex is that the latter can point to a diagnosis?medical proof explaining the cross-sex identification or mixed-sex feelings which some intersex persons experience. Still, the science of sex difference, particularly the effects of hormones on brain development and function, is still in its infancy. We may not have biological explanations for transgender today but we may very well tomorrow. In fact there are already hints from scientific research pointing in that direction. People who insist that transpersons should prioritize the body over the mind often forget that the brain is just as subject to sex hormones as genitals.