By Mark M. Green
Very few of us are free from some degree of discomfort in the presence of those who occupy the world in a manner different from ourselves. It’s not unreasonable to see that understanding the “other” is a path to greater acceptance and alleviation of that discomfort. Lately there has been considerable attention to an issue about people who are transgender, that is, those among us who are born as male or female babies but who discover, often at a quite early age that they are of the alternate gender. This is sometimes expressed by being trapped in the body of the wrong sex, a concept foreign to those of us who feel perfectly comfortable in the gender of our physical bodies.
However, as biological studies are teaching us, these physical characteristics of one or the other sex are not always in line with an individual’s perception (gender identity) of being male or female, or sexual orientation (heterosexual, homosexual or bisexual). The biological basis of sexual orientation was the focus of a prior column in this series: http://blogs.poly.edu/markgreen/2008/10/13/47/.
For now let’s focus on gender identity a subject I have been helped in understanding by a Dutch expert in the field, Dick F. Swaab, https://en.wikipedia.org/wiki/Dick_Swaab, whose research has greatly clarified the biological basis of what is termed gender disorder or better gender dysphoria. Independent of the sex our genes call for, XX for female and XY for male, we arise from a fertilized egg that is structurally sexually undifferentiated, a state we remain in for a considerable time. It takes almost two months after conception for this genetic information to arise from dormancy to begin to call for the changes that will, over time, fully distinguish the physical characteristics that distinguish male from female. This male/female distinction arises from the Y chromosome, which activates biological mechanisms to produce androgens, that is male hormones such as testosterone and dihydrotestosterone, which begin the path to the body’s physical changes that distinguish us around the second month after conception and then further along at puberty. The male genitalia in other words arise from an action, the production of a male hormone. Inaction arising from the absence of the Y chromosome leads to the female genitalia
However the brain, in contrast to the physical genitalia, does not receive information from testosterone to take on male characteristics until later months of pregnancy. A brain not receiving this hormonal information because of the absence of the Y chromosome proceeds to female characteristics. The fact that the information about genital characteristics and those of the brain occur at different times in the fetal growth, and can be influenced independently of each other, allows the possibility of gender dysphoria leading to the transgender state. The description above about testosterone and the Y chromosome describes a person with male genitals but a brain structure corresponding to the female state, so called MtF. The biological details of, on the other hand, FtM, transgender with female genitals and a male brain structure although less understood in detail, likewise arises from the fact that sexual differentiation of the brain takes place at a much later stage in development than sexual differentiation of the genitals. These two processes, development of genital sexual characteristics and brain structure can therefore be influenced independently of each other either in an MtF or an FtM transgender person.
Although male or female genitals are obvious requiring no scientific study of the individual, considerable research in several laboratories was necessary to demonstrate that MtF transgender people have certain characteristics of the female brain structure while FtM have male brain structure giving rise in both situations to gender identity independent of the person’s genitals. As Professor Swaab summarizes these facts: “There is no evidence that one’s postnatal social environment plays a crucial role in gender identity or sexual orientation… In fact, all current data indicate that gender identity and sexual orientation arise in the womb.” Experts in this field now generally accept that sexual identity is fixed in the womb and is not possible to change.
Helpful also in the preparation of this column has been Dr. Joshua Safer of the Boston University Medical Center (BUMC) who in attempting to alter the general attitude of many in the medical profession toward gender dysphoria and how people are treated by the medical profession has organized the BUMC Transgender Medicine Research Group.
In summary of a proper attitude toward transgender people one could quote Chaz Bono (formerly Chastity): “There’s a gender in your brain and a gender in your body. For 99 percent of people, those things are in alignment. For transgender people, they’re mismatched. That’s all it is. It’s not complicated. It’s not a neurosis. It’s a mix-up. It’s a birth defect, like a cleft palate.”
Science from Away: Transgender, the Facts
By Mark M. Green