Warning: Includes content that may be disturbing to some, including a brief description of a traumatic childhood accident.
In the 1960s, the theory of social conditioning was a dominant force in psychology. Researchers were exploring the ways that the world could shape our identities, and gender was one piece of the puzzle. Many psychologists believed that gender was learned — in other words, that it was just one more behavior sculpted by social influence.
This wasn’t idle watercooler talk. When psychologists met with intersex patients, they needed to help them make decisions about surgery, hormone treatments, and other medical interventions that would alter the course of their lives. (Intersex is a broad category that includes people who have sexual anatomy that doesn’t fit the typical definition of male or female.) Decades later, these cases help inform our understanding of gender.
One of the most dramatic examples is the case of David Reimer. In 1965, a botched circumcision with an electrocautery needle burned away eight-month-old David Reimer’s entire penis. His distraught parents made a life-altering decision, and brought him to see John Money, a celebrated psychologist at John Hopkins university, who had reputation as an expert in gender identity.
John Money knew he couldn’t recreate what David has lost, but he thought he could create a reasonable facsimile of female genitalia. He convinced the parents that David could still live a full and happy life — if his gender was changed and David was raised as a female. The fact that David had a twin brother also made the pair an all-too perfect test case for his theory that gender roles and sex preference could be reprogrammed by social influence.
Under Money’s direction, doctors removed David Reimer’s testicles. His parents changed his name to Brenda, and he was raised as a girl. When David reached adolescence, they used estrogen supplements to start puberty, causing him to develop breasts. And for 20 years, Money touted his success, wrote glowing research papers, and triggered a small avalanche of sex reassignment operations in difficult cases across the country.
David/Brenda was the ultimate experiment to prove the power of social conditioning over raw biology. Except it didn’t work. At two years old, David tore off dresses and fought to get toy cars and guns from his twin brother. In school, he was bullied mercilessly for his apparently masculine traits. At home, he told his parents that he felt like a boy. Meanwhile, Money wrote in an academic paper that “The child’s behavior is clearly that of an active little girl and so different from the boyish ways of her twin brother” — perhaps because David’s parents were lying to him, or perhaps because he was too deeply invested in his idea of gender malleability to perceive what was really happening.
When David finally learned the truth at age 14, he felt a sense of deep relief. With the help of testosterone injections, a double mastectomy, and genital reconstruction surgery, David returned to life as a man. Three years later, he married a woman.
Sadly, the changes were too little to late. David never fully recovered from his ordeal. At age 38 he committed suicide with a shotgun in a grocery store parking lot.
The case of David Reimer shows that gender can’t be changed by social intervention. It also raises an interesting parallel with transgender people who feel they are born as the wrong sex. In most cases, these feelings are powerful and undeniable. Like David Reimer’s feeling of wrongness, they start at an early age, far before puberty. And they resist social efforts to change them.
So what is the biological force that shapes gender identity? Increasingly, it seems that the answer lies in the prenatal environment of a developing baby.
The process begins with an ingredient called the SRY gene. The SRY gene lives on the Y chromosome, which means you only have it if you’re genetically male. When a male embryo reaches the sixth week of its existence, the SRY gene triggers a process that eventually leads to the creation of testicles (instead of ovaries). These new testicles begin to produce testosterone, and this testosterone jump-starts a range of change across the body — including in the brain.
We don’t fully understand the effects of testosterone on a developing brain. In studies of other animals, researchers have found that testosterone wires the brain for sex-specific behaviors like birdsong, building nests, and mounting potential mates. If you change the level of testosterone shortly before or shortly after birth, you end up with male animals that show more female behavior, or vice versa. These effects have been studied in a range of animals, including rats, hamsters, ferrets, finches, pigs, dogs, and sheep.
Human sexual behavior isn’t nearly as straightforward. However, there are human cases that hint at the powerful effect of prenatal testosterone. One example is girls who have a genetic condition called Congenital Adrenal Hyperplasia (CAH), which causes them to produce testosterone in the womb. Depending on the amount, their female genitalia may become enlarged and more masculine. Studies of CAH girls have been conducted in half a dozen countries, and they consistently find that CAH girls act a lot like boys. They prefer to play with boys, they favor rough play, and they’re more likely to pursue relationships with girls.
A reverse example happens with males who experience Androgen Insensitivity Syndrome (AIS). Although they’re genetically male, their bodies lack the hormone receptors that pay attention to testosterone. As a result, they develop as females. Some — like the Belgian model Hanne Gaby Odiele — grow up without being told about their intersex condition.
A similar effect may underlie transgenderism. When a fetus develops, the sexual anatomy develops first. It’s only later, in the second half of pregnancy, that the fetus begins to produce brain-altering testosterone. Some researchers speculate that these two steps can become split apart — for example, the SRY gene might trigger the development of male sex organs, but testosterone might fail to trigger the corresponding changes in the brain. What we do know is that studies consistently show that the brains of transgendered individuals have measurable differences. They are less like the brains of their natal sex, and more like the brains of the gender they feel they belong to.
No matter what biological processes underlie sex differentiation, one thing is obvious. Some parts of gender identity are hard-wired into our brains and bodies. No amount of tofu-eating, college experimentation, or immoral television shows can cause them — and no amount of therapy or social conditioning can change them. But our society is still struggling to accept this biological reality. Fifteen years after his death, we still haven’t fully learned the lessons from the tragic story of David Reimer.