Let's Talk About Sex

Biology is complicated. Kindness and respect don’t have to be. - Rebecca Helm.

Many people talk about sex and gender and most of them have very firm opinions despite having little understanding of biology. Many regard the issue as quite simple, as simple as the ‘obvious fact’ that there are two sexes and everybody is one or the other. Neat and tidy boxes make a simple life.

The biology most people encountered at school taught them that sex depends on a pair of chromosomes; if you have two X chromosomes (XX) you are female and if you have both an X and Y chromosome (XY) you are male. Easy.

It’s only in the advanced level biology class that we learn that there is one gene on the Y chromosome that matters to sex, the SRY gene. During embryonic development the SRY protein turns on male associated genes so having the SRY gene makes you genetically male. Sometimes, however, the SRY gene is not on the Y and sometimes it appears on an X chromosome.

If you have a Y chromosome but without the SRY gene then physically you will be female, genetically you are female, while chromosomally you’re male (XY). But if the SRY gene appears on an X chromosome you will be physically male and genetically male yet chromosomally female (XX).

Now sex-related genes turn on production of hormones is specific areas of the body, and reception of those hormones by cells in other parts of the body. ‘Hormonal male’ means you produce a ‘normal’ level of male-associated hormones, and, similarly, ‘hormonal female’ means you produce ‘normal levels of female associated hormones. We are, however, into the situation of two overlapping bell-curves or normal distributions. A small proportion of females will have a higher level of ‘male’ hormones than a small proportion of males. And vice versa.

Summing the possibilities, as you are developing your body may not produce enough hormones for your genetic sex, leading you to be genetically male or female, chromosomally male or female, hormonally non-binary and physically non-binary. Actually, that’s still too simple. Cells have receptors to receive the signals from sex hormones, but they don’t always work. It all leads to a body that can be anywhere from male, through non-binary, to female.

Can we point to what the absolute cause of biological sex is? Can we safely label people? Is it fair to judge people by it?

We could appeal to the numbers, after all surely, it’s safe to say that most people are either male or female? As Rebecca Helm[i] put it:

Biological sex is complicated. Before you discriminate against someone on the basis of biological sex and identity, ask yourself? Have you seen YOUR chromosomes? Do you know the genes of the people you love? The hormones of the people you work with? The state of their cells? Since the answer will obviously by no, please be kind, respect people’s right to tell you who they are, and remember that you don’t have all the answer. Again: biology is complicated. Kindness and respect don’t have to be.

This has been a very brief and introductory comment, far from exhaustive as to the complexity of biology. There is much more.  And we haven’t begun to think about how our brain interacts with all this stuff – but that’s for another day, although it’s the most important part.

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[i] Helm, Rebecca, from a thread on Twitter @RebeccaRHelm 12/19/2019