In many societies throughout history, including most of the Western World today, ‘biological sex’ has been, and continues to be treated as a dichotomy – you’re either male or female, no questions asked. Simple enough, right? Except for the fact that it just doesn’t work that way. The differences between ‘male’ and ‘female’ bodies aren’t as vast as they’re often implied to be. The most obvious evidence for this is the existence of intersex children who are born with ambiguous genitalia. With the exception of the vagina itself, male and female genitalia are really not that different – the clitoris is very similar to the penis, the labia to the scrotum etc. The vast majority of the time, ambiguous genitalia poses no threats to the child’s health, yet most of the time surgery is still done to make the genitalia appear more ‘acceptable’, so that the child ‘fits in’. After all, how could a girl possibly live a normal life with a larger than average clitoris? Shock horror. And this is solely if you focus specifically on genitalia. ‘Sex’ as it is often used actually signifies countless different variables which are lumped in together with either ‘male’ or ‘female’. So this includes not just genitals, but also chromosomes, hormone levels, breasts or lack thereof, body hair, bone structure etc. Not only is there vast variation in almost all of these categories even within ‘dyadic’ males and females, but most of these can also be altered or changed, either with or without outside influence. One aspect of sex that remains static, however, is the arrangement of sex chromosomes. As most of us were taught at school when we were 9 or thereabouts, XX =girl, and XY = boy. Once again, it’s not that simple. For a start, there are far more possible combinations than simply XX and XY. While rare, other possible combinations include XXY, XYY, XXX and X, among others. In fact, it’s also possible for someone who’s ‘male’ to have XX chromosomes, and for someone who’s ‘female’ to have XY chromosomes. This is because most Y chromosomes have a specific gene which triggers the development of testes. However, mutations in these chromosomes mean that sometimes, the Y chromosome might contain no such gene (leading to an XY female), or an X chromosome might contain said gene (resulting in an XX male). In effect, most people can’t be 100% sure what their chromosomes are, because they’re usually only tested if a chromosome related disorder is suspected. Long story short, the notion of ‘biological sex’, at least in the traditional sense, is heavily flawed. Even amongst those whose sex is seen as unambiguously male/female, there’s still massive variation in countless areas such as hormone levels (which in itself affects many areas of body development) and skeletal structure. Trying to lump all of this variation into one of two boxes is an outdated practice and doesn’t really help anyone.