Who we are is complex. It incorporates many aspects of where we grew up, how we identify ourselves, how others identify us, actions we have taken in the past and who we would like to grow into. Identity can be fairly solid, it can shift fluidly, or migrate through a series of stages. I turns out that human biological sex is not binary like we were taught.

Once aspect that is a key component to how we see ourselves and how society sees us is biological sex. I was going to write a big thing about it, but then SciShow on Youtube did it for me.

This episode was written by Carly Britton and covers many aspects that are worth listening to.

In short, human biological sex is not binary, it is a spectrum, and it isn’t necesarrily a single spectrum either.

A binary division is where you attempt to divide a thing into 2 parts. Some handy examples that make sense is dividing numbers into numbers that have enlcosed sections (6,8,9,0) and open sections (1,2,3,4,5,7). However some groupings defy easy binary division based on a simple rule, such as trying to binary divide fruit into sweet and sour. While it is easy to identify some fruits that everyone agrees is sweet and some that are sour, there are a number of fruits that either defy easy identification or fit into yet another category of “it depends”.

Every aspect of what we may think of as “male” or “female” is frequently found in various subsections of human populations, but no single aspect is sufficient to describe all humans. For example if we consider chromosomes, the DNA of our sex expression, we were taught in school the simplified version that males have the XY chromosome expression and females have the XX chromosome expression. While it is possible to create a binary divide of XX is female and all others are male, it becomes very awkward when we have the so called sex chromosome be X, or Y, or XXX, or XYY and so on. Many people who appear female and identify as female have a sex chromosome that is not XX.

An image of various sex chromosomes with additional X's, known as Clienfelter Syndrome. Attribute Wikipedia for the image.
Klinefelter syndrome – the presence of additional X chromosomes
By User:Nami-ja – Own work, Public Domain,

Additionally when we add in any other sex identifier to the mix we find that a binary division is impossible. There is not even really a spectrum from “female” to “male”.

Another aspect to consider is the difference between assigned sex and chosen sex. While all the traditional markers for categorising someone as a particular sex, the person may not identify themselves as this sex. This person may chose to make no changes in appearance, cosmetic changes, medical changes and or surgical modification to correct this misalignment. Since the definition of who actually fits into the overly simplistic physical definitions of “male” or “female” are poor, it seems odd to then require that someone who fits the physical criteria is then also required to ignore the very important criteria of “self identification”.

It is also odd to try to fix this by just creating a third category of “neither”. If we look at a simple spectrum such as the rainbow of visible light, it is made of either red, blue or “other”. Applying this third category solution means that orange and violet are considered to be the same, when clearly they are not. And where does watermelon and maroon fit?

Sex identity is complex and involved a number of features such as DNA/chromosomes, gene expression, development, hormones, cosmetic appearance, taste and self identity. To lump all of these aspects into a false binary, or stretch it into a false trinary is hurtful to people who find themselves excluded or poorly labelled for no good reason.

To minimise this hurt, it is important to accept when someone identifies other than your initial evaluation of them and if a person is dressing ambiguously, accept that they may not identify as any simplistic label. It is not offensive to ask someone if they have some prefererd pronouns, and accept if the pronouns someone prefers does not align with your assumptions or comfort.