There Is “Biological Evidence For Gender Identity,” But That Doesn’t Mean It’s Immutable

By the time a scientific controversy percolates down to the popular press, it’s inevitably been distorted. That’s not intentional. Most of the time, reporters don’t have the background necessary to understand the original research, and nuances get lost in the retelling. Unfortunately, readers usually don’t have access to original scientific papers. So, it can be difficult to separate fact from hyperbole.

One such distortion occurred recently when Steven Rosenthal (a pediatric endocrinologist at Benioff Children’s Hospital) published an article supporting the so-called, “affirmative model” (rapid social and medical transition) for treating transgender and gender-diverse (TGD) youth. It appeared in the journal, Nature Reviews of Endocrinology, and a companion article is scheduled to be published in the Annual Review of Medicine. 

Rosenthal’s enthusiastic support of the “affirmative model” is based on his belief that “gender identity” is biologically based and, therefore, permanent and immutable. Hence, the more rapid the transition the better. In response, Jay Cohn (of the Society for Evidence-Based Gender Medicine) critically analyzed both of Rosenthal’s papers in the Journal of Sex & Marital Therapy. (All three PDFs are here.) 

Cohn’s main criticism of Rosenthal is that there is no definitive evidence that “gender identity” is biologically based and, consequently, it can change at any time. Hence, medical intervention for TGD youth should be cautiously postponed, if not avoided altogether. A summary of Cohn’s rebuttal was published on the SEGM website. In turn, several popular websites ran stories based on the SEGM summary, one under the headline, “No Biological Evidence For ‘Gender Identity’ Exists, Group Of Scientists, Researchers Says.” By this time, the question of biology’s potential role in “gender identity” had become garbled, and the headline was quite misleading. Unfortunately, that headline is what people are going to remember.

Confusion over biological ‘causation’

In support of his belief that “gender identity” is biologically based (hence, permanent and immutable), Rosenthal cites a number of scientific studies claiming to have found genetic or neurological differences between people who trans-identify or have gender dysphoria, and people who do not. Rosenthal’s assumption is that any biological differences between these two groups is evidence that “gender identity” is a fundamental, “ingrained” (permanent) personal characteristic. In rebuttal, Cohn explains the methodological flaws in each of the studies that Rosenthal cites and concludes that because no one has been able to definitively identify a specific biological correlate of “gender identity,” it has no biological basis and is both impermanent and alterable.

Whether you agree with Rosenthal or Cohn on the timing or necessity of medical intervention for TGD youth, it’s important to understand they both base their arguments on fundamental misunderstandings of biology and the role biology plays in subjective self-perceptions, including “gender identity.”

In the original paper, Rosenthal defines “gender identity,” as one’s “… inner sense of self as male or female or elsewhere on the gender spectrum.” To my mind, this is a reasonable definition. People are free to self-identify however they wish. He also correctly recognizes that “gender identity” exists separately and is distinct from sex (i.e., being male or female; Although he does confuse sex with certain developmental disorders.) In keeping with his definition of “gender identity,” Rosenthal goes on to say that “… gender identity can only be assumed and not known until an individual reaches a particular level of psychological development and self-awareness.” This is true. I can’t know what you think about yourself until you can tell me. Of course, this does not mean that I have to agree with you or affirm your self-perception. It just means that your self-perception is your self-perception. It’s unknowable unless you reveal it.

Rosenthal also correctly explains that gender identity is distinct from gender expression, gender roles, and sexual orientation. In his words, “… a girl could display masculine behaviors but exclusively identify as female, or a boy could display feminine behavior but exclusively identify as male,” and either could be attracted to either sex. Again, this makes sense.

The problems arise when Rosenthal, Cohn, and (and others) confuse the idea of “gender identity” with some specific biological structure or condition, and misunderstand the causal role that biology — neuroscience in particular — plays in self-perceptions. It’s these confusions that are hobbling our ability to understand and discuss complex psychological issues like “gender identity.”

First, consider the fact that “gender identity” is neither an easily recognizable ‘thing,’ like a brain or a leg, nor a clearly defined biological condition, like being pregnant or hypothermic. The term is a metaphorical category — as are all psychological terms — that refers to a variety of different self-perceptions each of which will be represented by a variety of unique brain states (neural activity patterns in your brain). Consequently, “gender identity” is a product of biology because brain activity is biology. 

For instance, although you and I may self-identify using a similar term (e.g., “liberal”), our belief systems are going to differ somewhat because, by definition, we think differently. The term, “liberal” is not going to mean exactly the same thing to me as it does to you. So, our belief systems will be represented by somewhat different brain activity patterns. Even if our subjective identities were precisely equivalent, however, they would be represented by different brain activity patterns because we are unique people with unique brains. Further, the patterns of activity that represent the concept will change somewhat from time to time. There is not one specific identifiable pattern of brain activity that represents each specific idea that we have.

By Rosenthal’s own definition, “gender identity” is a subjective self-perception. Consequently, it can’t be represented by a specific, identifiable brain structure, a discrete set of brain cells, or a specifically identifiable pattern of neural activity. That’s not how brains work. However, the fact that you can’t point to a specific structure or pattern of brain activity and say “Look, there’s your gender identity,” doesn’t mean that it’s not a product of biology. Our self-perceptions (or “identities”) are emergent properties of widespread neural network activity patterns that vary from time to time within and between individuals. That means that my self-perception can’t be “discovered” by looking for some unique biological marker in my brain and comparing it to some hypothetical neural activity in your brain.

Further, the fact that gender identity is a product of brain activity (i.e., biology) does not mean that it’s necessarily “ingrained,” deterministic, won’t change over time, or that we can (or will be able to) see its imprint in an MRI, blood test, or DNA sequence. These are fundamental misunderstandings embedded in both of Rosenthal’s papers and implicit in Cohn’s rebuttal.

Conversely, of course, the fact that your self-perceptions don’t show up in an MRI, blood test, or DNA sequence does not mean that they don’t exist, or that they’re not a product of biology. That’s a misunderstanding held by most of Rosenthal’s critics.

So, when Cohen writes this, he’s absolutely correct:

In sum, there is no currently available test (brain, DNA, or otherwise) that can reliably differentiate between a trans-identified and a non-trans identified person, which Rosenthal (2021) acknowledges: “(n)o currently available laboratory test can identify an individual’s gender identity”

That’s true for the same reason that there is no test “brain, DNA or otherwise” that can reliably differentiate between someone who identifies as an extra-terrestrial lizard person (like Durek Verret) and someone who identifies as a normal human. But that doesn’t mean that these self-perceptions aren’t influenced or underpinned by biology.

Cohn is also correct in pointing out that “People vary in the intensity of their gender identification and in the permanence and completeness of this feeling. One’s feelings of being a man and/or woman may fluctuate…” (from Bockting, 1999). This statement is entirely consistent with what I know about neuroscience. Our self-perceptions can — and often do — change over time (as do our brains). This is precisely why there are large cohorts of people whose gender identity changes as they mature, and who choose to detransition. In fact, it makes no psychological or biological sense to assume that a self-perception will not change over time.

There’s one additional point to be made about this statement from the SEGM summary: “there is no brain, blood, or other objective tests that distinguishes a trans-identified person from a non-trans identified person.” This is true and, most likely, will always be true. The reason is that “trans-identified” and “non-trans identified” do not refer to specific, discrete groups of people. They, too, are categories each of which contains a very diverse group of individuals with very different motivations, self-perceptions, and points of view. Consider this analogy: There is no single diagnostic test that can determine if someone is on the autism spectrum or has Alzheimer’s, but that doesn’t mean that these conditions don’t exist, or that they’re not underpinned by biology.

So, you can see how the claim “No Biological Evidence For ‘Gender Identity’ Exists…” is misleading on two levels. First, there is biological evidence that gender identity exists: Human beings — which are biological entities — hold these beliefs, report these beliefs, and behave according to these beliefs. Second, the claim makes the rather naïve assumption that ‘real’ biological evidence has to be some identifiable set of brain cells, specific gene sequence, or detectable set of molecules circulating in the blood. This assumption is incorrect. “Gender identity” is an emergent psychological phenomenon that is the product of dynamic, ongoing neural activity.

The key point to remember is that cells, genes, or molecules don’t have gender identities any more than your lungs or liver can fall in love. Complex psychological phenomena — like gender identity, or being in love — only exist at the level of the whole, intact person. The tacit assumption that because our mental states are products of biology, there should be a specific diagnostic test that reveals their existence is a misunderstanding of how biology works.

The most compassionate, kind, and thoughtful approach to this issue would be to decouple ideology, politics, and the financial interests of the biomedical industry from science, and work cooperatively to better understand humanity in all its diversity. In Cohn’s words, “There are serious challenges in deciding how to best support those currently suffering gender dysphoria, given how little is known about this complex condition. Accurately describing what the evidence currently says and does not say, and what further evidence is needed, is crucial.” I agree.

Epilogue

Diversity, including neuro-diversity, should be recognized and valued. Every individual should be respected, accepted, included, and have the opportunity to live the best life that they can. For some people, pharmacological or surgical intervention may be the best option. However, by definition, that singular solution is not appropriate for everyone, just like the same high blood pressure medicine or antidepressant doesn’t work for everyone. Unfortunately, the most zealous proponents of that singular solution are doing a tremendous amount of irreversible damage to the young, the vulnerable, families, women, and many of our institutions. I find that both misguided and unacceptable.