Some of these discoveries begin to explain things about gender identity that otherwise strike us as puzzling. A person who is genetically XY with male gonads and a typical male body may not feel at all right as a man. So far as gender is concerned, he feels completely female. Conforming to a male role model may cause acute misery and dissonance, sometimes ending in suicide. Conversely, a woman who is genetically XX may feel a powerful conviction that she is psychologically, and in her real nature, a man. Sometimes this disconnect is characterized as a female trapped in a man’s body or a male trapped in a female’s body. Statistically, male-to-female transsexuals are about 2.6 times as common as female-to-male transsexuals.
Is this conviction on the part of the person not just imagination run amok? In most cases, the matter is purely biological. Once we know something about the many factors, genetic and otherwise, that can alter the degree to which a brain is masculinized, it is a little easier to grasp a biological explanation for how a person might feel a disconnect between his or her gonads and his or her gender identity.
For example, in fetal development, the cells that make GnRH (gonadotropin-releasing hormone) may not have had the normal migration into the hypothalamus. If this happens, the typical masculinization of the brain cannot occur. For some individuals, the explanation of the chromosome-phenotype disconnect (XY but has a female gender identity) probably lies with GnRH, despite the existence of circulating testosterone in the blood. It is noteworthy that the data indicate that most male-to-female transsexuals do have normal levels of circulating testosterone, and most female-to-male transsexuals do have normal levels of circulating estrogen. This means that it is not the levels of these hormones in the blood that explains their predicament. Rather, we need to look at the brain itself.
Examining brains at autopsy is currently the only way to test in humans whether an explanation for a behavioral variant in terms of sexually dimorphic brain areas is on the right track. Here is some evidence that it is. First, there is a subcortical area close to the thalamus called (sorry about this) the bed nucleus of the stria terminalis (BNST). The BNST is normally about twice as large in males as in females. What about male-to-female transsexuals? Because the data can be obtained only at autopsy, they are limited. Nevertheless, in the male-to-female transsexual brains examined so far, the number of cells in the BNST is small. The number looks closer to the standard female number than to the standard male number. For the single case coming to autopsy of a female-to-male transsexual, the BNST looks like that of a typical male.
What are the causal origins of this mismatch of gonads and brain? The answers are still pending, but in addition to the many ways in which lots and lots of genes could be implicated, various drugs taken by the mother during pregnancy are possible factors. What drugs? Among others, nicotine, phenobarbitol, and amphetamines.
Like many others of my generation, I first learned about transsexuality when the British journalist and travel writer James/Jan Morris was interviewed on the BBC in 1975. A highly gifted and clearheaded writer with a wonderful sense of humor, Morris discussed her long struggle with the dilemma of feeling undeniably like a female from the age of 5 and yet possessing a male body and presenting to the world as a male. In Morris’s forthright book on the subject, Conundrum, she provides one of the deepest and most revealing narratives on what it is like to be unable to enjoy that calm sense of being at home in your own skin, of being one with yourself. Morris had married a woman to whom he was deeply attached and had five children. By all accounts, he was a wonderful and devoted father. But as the years went by, he became ever more miserable until in his 50s, and with the blessing of his wife, he underwent the long and difficult process of a sex change. Here are Morris’s heartfelt words describing the change: