You don’t have a male or female brain – the more brains scientists study, the weaker the evidence for sex differences
In other words, sex is a very imprecise indicator of what kind of brain a person will have. Another way to think about it is every individual brain is a mosaic of circuits that control the many dimensions of masculinity and femininity, such as emotional expressiveness, interpersonal style, verbal and analytic reasoning, sexuality and gender identity itself.
Or, to use a computer analogy, gendered behavior comes from running different software on the same basic hardware.
The absence of binary brain sex features also resonates with the increasing numbers of people who identify as nonbinary, queer, nonconforming or transgender. Whatever influence biological sex exerts directly on human brain circuitry is clearly not sufficient to explain the multidimensional behaviors we lump under the complex phenomenon of gender.
By Lise Eliot, Professor of Neuroscience, Rosalind Franklin University of Medicine and Science