For years at 13.7, Barbara J. King has been writing about what she calls the spectrum of gender expression, and "the fact that gender identity isn't only — or even mostly — about biology and that it's most certainly not reducible to the sex one is assigned at birth." That's an especially important lesson in light of new research that identifies one of the sources of prejudice against transgender individuals: the (mostly mistaken) belief that men's and women's stereotypical characteristics do, in fact, come down to some immutable feature of one's biology.

Transgender people like myself have consistently tried to promote the idea that sex and gender are two distinct qualities that every human possesses. Meanwhile, our adversaries believe that sex (chromosomes or genital morphology at birth, or both) completely determine what our gender should be...and if we deny that, we are committing deception.

There is a new study by Boby Ho-Hong Ching and Jason Teng Xu in the journal Sex Roles (The Effects of Gender Neuroessentialism on Transprejudice: An Experimental Study) that examines the effects of that adversarial belief.

Ching and Xu presented 132 university students in Hong Kong with one of three articles to read. One article was intended to reinforce the idea that gender differences have a biological basis, one was intended to question this view, and a third was entirely unrelated to gender differences and served as a baseline comparison.

The article advocating a biological basis for gender presented a study purporting to find that "the brains of men and women are wired up differently," which "could explain some of the differences in personality and behaviour between male and female." It went on to describe the study and quote fictional experts, including "Professor Schneider," who summarized: "There is a neurological cause of sex differences, which suggests that these differences are difficult to change."

The alternative article reported the same study, but also included some cautionary remarks. For instance, the researchers noted that men and women "still have many similarities in terms of the brain architecture" and that "the relations between brain and human behavior are complex." In this version, Prof. Schneider instead warned that the studies do not "offer insights into the socio-biological developmental processes that lead to observed male/female differences...The neurological associations with sex differences are not fixed, but amenable to change by environmental factors."

The students were then asked various questions about transgender individuals and the stereotypes associated with us, their attitudes towards us and whether civil rights should be accorded to us.

The researchers found that those participants who had read the article endorsing a biological basis for gender differences were significantly more likely than participants who read either of the other articles to report negative stereotypes about transgender individuals, to report prejudicial attitudes, and to reject equal rights. Responses for participants who read the alternative article or the control article did not differ from each other.

The authors suggest that the article endorsing a biological basis for gender differences reinforced what psychologists call an "essentialist" view of gender — the idea that men and women belong to fundamentally different categories that have some inherent basis (some "essence"), such that the categories have sharp and immutable boundaries, and such that members of the same category share many important similarities with each other. On a view like this, it's hard to make sense of a mismatch between a person's gender identity and their assigned sex, if it's the biological basis for their assigned sex that's taken to reflect their true "essence." This, in turn, could support a more prejudicial attitude towards people who identify with a gender other than the one assigned at birth.

There have been other such studies, some of which have reached similar conclusions.

The new study by Ching and Xu goes beyond this prior work in showing a causal relationship between beliefs about the biological basis of gender and a host of beliefs about transgender individuals, with a particular role for the essentialist commitments that a biological basis is taken to entail. Among other things, the findings suggest that if people appreciate the non-dichotomous and diverse nature of gender identity, they're less likely to maintain negative views towards people who are transgender, and less likely to oppose their rights.