Scientist and GenderGP community member, Samantha Jane, shares her thoughts in this guest blog on why she feels the binary model of gender is outdated.

Samantha Jane is a transgender woman living in Sweden. She is a trained scientist and works in the aerospace industry. She writes on transgender topics to raise awareness of transgender issues and the science behind sex and gender.

The following article does not necessarily represent the views of the publishers.


Redefining the binary

When we talk about biological sex we are conditioned to think of it as binary, male and female. Normally doctors assign those humans with XX chromosomes to the female group and XY chromosomes to the male group. Most non-doctors, however, seem to assign a biological sex on the imagined condition of the person’s genitals.

Of course we are all aware of those with chromosomes that do not fit within this binary or who have genitals at birth that do match the perceived “norm”. There is an ongoing discussion in the media about intersex people and whether they should be classified as male or female, just look at the controversy surrounding Castor Semenya.

It is estimated that up to 1.7% of the population could be born intersex, or with “different” sex traits, however, there is no good science-based definition of what the term intersex actually means and how these people are categorised. Modern science is, however, starting to redefine biological sex and some geneticists and doctors now believe that talking about binary biological sex is in fact incorrect or, at best, misleading.

A report in Scientific American, published in 2015, caused a small ripple when it detailed how science is showing that almost everyone is a patchwork of genetically distinct cells and these cells do not necessarily match the sex of the rest of the person’s body. Indeed, it is now thought that the sex of each cell is behind the behaviour of the cell. John Achermann, a researcher at the Institute of Child Health at University College in London, was quoted as saying: “I think there’s much greater diversity within male or female, and there is certainly an area of overlap where some people can’t easily define themselves within the binary structure.


It’s complicated…

Biological sex determination, it turns out, is actually much more complex than first thought. Various genes can switch on or off particular gonad development independent of the chromosomes. Indeed, recent evidence suggests that this can happen throughout life and that by switching a gene on, one can change ovarian cells into sperm cells and vice-versa.

Scientist studying sex disorders have also found 25 genes that seem to play a role in sex determination. However, they have such a mild effect that they may go unnoticed by the carrier. An example is of a 70 year old man who was operated on for a hernia. It was found that despite fathering four children, he had a womb that had previously gone unnoticed.

Indeed, it seems as if many scientists are coming to the conclusion that it is meaningless to talk about sex as a binary.

So how can “biological sex”, a term some scientists and doctors avoid, be assigned? Chromosomes? Genitals? How much of your body has to be “female” to define you as such? The truth may be that it is actually impossible, perhaps nobody has 100% male or female biological sex characteristics and we are beginning to understand that biological sex isn’t all about your genitals.

So if biological sex isn’t binary what is the implication for gender? Obviously an important question for the genderqueer/transgender community.


What does this mean for gender?

A telling place to start is the Endocrine Society, a world-leading global organisation, which, in a 2017 positioning paper said: “Considerable scientific evidence has emerged demonstrating a durable biological element underlying gender identity”. This is a statement backed up by many studies. For example, researchers found that

in nine of the 23 identical twin pairs, both siblings were transgender, whereas in no case among the 21 same-sex fraternal twin pairs were both twins transgender.

Telling evidence for a genetic component to being transgender. And it doesn’t stop there – brain structures in those people identifying as transgender also seem to have a genetic component. Neuroscience studies from 1995 and 2000 show that certain brain structures that exhibit sexual dimorphism are, in trans people, more like the cis people they identify as, rather than the brains of those that are similar to their biological sex (assuming conventional identification). Some brain properties and regions also appear closer to the gender the trans person identifies with, while in some cases trans people appear to have structural differences to cis people.

Furthermore, a study in 2009 showed that transsexuals have a distinct grey-matter variation in the brain. While another study in 2011 showed that the white matter microstructure in the brain of trans masculine people matched their gender rather than their birth sex.

Let me be clear, none of this means that there isn’t a component to transgender people that is nurture/society driven. But these very new studies, of which more and more are being published, seem to make it clear that there is no hard and fast biological sex divide, we are all a mixture, to some extent, of what might be thought of as male and female. Following on from that many researches, including the best endocrinologists in the world, believe that there is, to some level, a genetic underpinning to transgenderism.

From a personal view this makes a lot of sense but to many these findings will be both scary and threatening. The West has for two thousand years or more been based on an immutable difference between men and women. Our society and beliefs are based on a clear, succinct difference between male and female. Our societal structures require us, at the moment, to define ourselves as one or the other. Yet as we can see, even biological sex – and certainly gender – is not as clear cut as it once seemed.

Perhaps one day, probably not in my lifetime, we will see a world where it doesn’t matter what chromosomes you have and what genitals you hide beneath your clothing. It won’t matter what you call yourself because there will be no distinction – we will finally all be human.


Find out more about non-binary identities




Sammi Smith, is a scientist and GenderGP community member.