When it comes to understanding gender, we are often told to start with biology. Chromosomes, hormones and anatomy form the standard framework for defining what it means to be male or female. But I've come to believe that this framework—while useful in certain contexts—is fundamentally flawed when it comes to understanding gender identity.
To me, biological sex is like a bottle. It has a shape, a colour, a material. But what really matters is what’s inside. The contents. The substance. In this analogy, the bottle represents the body and the contents—milk, juice, water—represent gender identity. What makes a person a man, a woman, or nonbinary is not the bottle they were born in, but what they carry within them.
This isn’t just a poetic metaphor. It’s also aligned with a growing body of neuroscience that suggests gender identity might have roots in brain structure—material, biological differences in the brain that are independent of reproductive anatomy. Some trans individuals have brain patterns that more closely resemble those of their identified gender rather than their assigned sex at birth. These differences aren’t just theoretical—they show up in scans, in developmental pathways and in lived experience.
Critics often point to chromosomes or genitalia as the final word on gender. But if we accept that the brain is the seat of the self—of thought, feeling, identity—then surely it should be given greater weight than the body parts we can see. After all, we don’t define a person’s personality, intelligence or emotional world by the shape of their feet or the number of ribs they have. Why should gender be any different?
I believe gender types are innate. Not learned, not conditioned, not a result of cultural programming—but built in, hardwired, perhaps even before birth. That’s why attempts to “correct” gender identity through social pressure or behavioral therapy don’t work. You can’t pour milk into a bottle of juice and expect it to become juice. The contents are what they are.
And this is why I see the recent debates over legal definitions of sex and gender as missing the point. Courts and governments can legislate bottles, but they cannot legislate contents. The law may define “woman” by anatomy, but many trans women live every aspect of their lives as women—not because of surgery or clothing, but because of who they are on the inside. That reality deserves recognition.
It’s important to acknowledge, though, that the science around gender identity is still in its infancy. While there is growing evidence pointing to biological factors—such as brain structure and hormonal influences—there’s no single, conclusive explanation yet. The relationship between gender identity, brain patterns and genetics is complex, and we are still learning how these aspects fit together.
That said, the point I’m making isn’t that gender identity can be reduced to biology alone. Instead, it’s that the biological aspects—particularly those related to brain function—deserve more recognition in the conversation. Much like how we don’t reduce a person’s intelligence, personality or emotions to a single biological feature (like the size of their brain), gender identity should not be defined solely by physical markers. It’s the lived experience—the internal sense of self—that truly defines us.
In the end, we have to ask: what makes a person who they are? Is it the visible, the measurable, the externally assigned? Or is it the felt, the known, the lived experience of being? For me, the answer is clear. It’s not the bottle that defines us—it’s the contents.
