Biological Sex: A Lie Dressed as Science

The concept of “biological sex” is not ancient.

They say biological sex is fixed — that it follows us from birth like a curse or a blessing. That it’s natural, objective, impossible to question. But I ask: where does this divine certainty come from? Who decided that something as complex as the body can be reduced to a binary label?

The truth is, the concept of “biological sex” is not ancient. It’s not universal. It’s not neutral. It was born out of the need to justify inequality — to fix differences and create hierarchies.

The idea of regulating bodies based on perceived sex has existed for centuries, especially through religious and cultural traditions. However, the specific scientific concept of “biological sex” as a fixed, objective, and universal category only started to emerge in the 18th and 19th centuries.

During this time, modern science, especially biology and medicine, began to create classification systems to organize and explain living beings, including humans. This scientific codification helped solidify the binary understanding of sex as “natural” and “unchangeable,” giving old beliefs a new form of authority.

Before that time, the difference between body and gender didn’t exist like it does now. People were called men or women depending on their social role, status, or power. The body was mostly a tool, a function.

But when the idea of gender appeared in the 20th century — as a social construction — a counterweight was needed. Something that looked strong and solid: biological sex. A way to say: “Okay, gender can change, but sex stays the same.”

Stays the same according to who? Based on which criteria? Why should a mix of bodies, hormones, genitals, chromosomes, and behaviours be reduced to “male” or “female”?

Real biology is diverse. It changes, evolves. There are intersex people. There are hormonal levels that don’t follow binary patterns. There are genetic variations that break simple definitions. There are women without reproductive organs. Men without penises. And bodies that don’t want to be defined at all.

But society doesn’t want to understand — it wants to control.
Biological sex becomes a tool to decide which bodies can enter which spaces, get which jobs, receive which rights.
It’s like a code, used to limit movement, thought, and expression.

And the most dangerous part: this concept is presented as science. As if it’s neutral. As if it carries no ideology. But in reality, it’s a discourse — a way of speaking — created in a specific historical moment to answer needs of control and normality.

Real science — the one that questions, learns, and evolves — already knows that sex is not binary.

Anne Fausto-Sterling and others have shown that sex is multidimensional.
There is no single thing that defines whether someone is a man or a woman. Not chromosomes. Not hormones. Not genitals. No single part of the body can speak for the whole.

But the problem is not science. It’s how people use it. Like the Bible, or the Constitution, science is used as a shield to support old beliefs. People don’t read it to understand — they twist it to control.

That’s what we’re seeing today: an obsession with defining, closing, categorizing. Not to protect anyone — but to keep power over bodies.
Especially bodies that don’t fit the mold. The ones that refuse the script. The ones that cannot be domesticated.

And yet, they are here. Despite fear. Despite symbolic violence. Despite stigma. They are the bodies that don’t ask permission. The voices that don’t wait for approval. The flesh that challenges the label.

Saying that biological sex is unchangeable is denying the diversity of life.
It means trying to silence exceptions because they break the system.
It means forcing a literal reading on something that is alive.

Because yes — as everyone knows — trans, intersex, and dissident people are clearly not biological beings, right? They’re like those “bio” yoghurts that had to change their name because they weren’t pure enough for the rules.
Apparently, these bodies aren’t “biological” enough either. And that, more than anything, seems to be what really bothers them.

A closing poem for the article:
Bodies were never truly free,
for someone once tried to define them.
When it seemed we were moving forward,
certain voices rose again.

The victories that spoke of freedom
were silenced by distant screams,
while liberty vanished slowly
beneath the lie of safety.

And those who could now be themselves
were judged again,
by eyes that did not understand
and rules that were never real.

The binary, once a bridge,
now tightens like a wall,
leaving no room to breathe.

And suspicion returned,
falling — as always — on the same ones:
the women,
who could no longer dream of freedom,
because some sisters had decided
that judging was safer than embracing.

I hope this poem speaks to you, wherever you are.
Did it make you think? Did it touch something inside you?
Feel free to share your thoughts — I believe that every voice counts,
especially when the world tries to silence us.