How can someone’s gender differ from the sex they were assigned at birth?
What neuroscience can tell us about gender identity and what the DSM actually says (November 2026)
I wrote this in response to people who say or imply that being trans is a sign of mental illness.
At birth, sex is usually assigned based on visible anatomy. Gender identity is our inner sense of our gender. Research suggests that genes and exposure to hormones before birth may help shape that sense of self. Studies have also found differences in brain structure and function, though researchers are still working out what those findings mean.
These findings offer clues to why someone’s gender identity can differ from the sex they were assigned at birth. How those influences come together for any one person is still an open question. And how our sense of gender develops is a different question from when we recognize it or find words for it. For some of us, that takes decades.
The DSM-5-TR answers a different question. It defines gender dysphoria as a diagnosis that requires clinically significant distress or difficulty functioning related to a difference between a person’s experienced gender and their sex assigned at birth. Some trans and nonbinary people experience that distress and deserve care for it. Being trans, nonbinary, or gender nonconforming is not itself a mental illness. Calling people mentally ill simply because of who they are is both scientifically unjustified and unkind.
Don’t take my word for it. Copy and paste this into your favourite AI tool and ask, “What sources support these claims, and where is the evidence still uncertain?” Or start with the links below and see what the researchers and the American Psychiatric Association actually say.
Here’s my bottom line. When the Nazis came to power, they persecuted trans people, shut down their publications, and dismantled the Institute for Sexual Science, which had provided care and support.
So when people are bullied, disowned, denied their rights, or punished for being trans, I have a question for anyone defending that treatment. What exactly are you defending, and whose side of history do you want to be on?
Research review on how gender identity develops: https://pubmed.ncbi.nlm.nih.gov/31027542/
American Psychiatric Association on gender dysphoria: https://www.psychiatry.org/patients-families/gender-dysphoria/what-is-gender-dysphoria
Historical research on Nazi persecution of trans people: https://www.cambridge.org/core/journals/central-european-history/article/transgender-life-and-persecution-under-the-nazi-state-gutachten-on-the-vollbrecht-case/0779A24B130C4F0CA64DB639FA6DBF46
Final thought
If you’re having a baby, postpone that gender reveal party until your kid tells you who they are. Be prepared to wait a few years for that answer. In the meantime, remember that unconditional love is the best soil for a healthy blossoming.
And one more thing. Being trans isn’t a lifestyle choice. Refusing to learn about trans people is a choice.