So this is probably an unpopular opinion but I think the term “biological sex” is meaningless, as is the distinction between sex and gender. While I continue to hear trans people use it and share it in various forms such as the problematic genderbread person, it is primarily used by cisgender people as a way of convincing themselves that the binary does exist in some form even if they support diverse gender identities. But as a biologist (by training) and a real life trans person™, I am here to tell you that it is just as much of a shared illusion as binary gender.
Hopefully by now you are aware of the existence of intersex people. According to the Intersex Society of North America, “intersex is a general term used for a variety of conditions in which a person is born with a reproductive or sexual anatomy that doesn’t seem to fit the typical definitions of female or male.” Without going into excruciating detail because you should hear it from intersex people themselves , both chromosomal sex and reproductive organ configuration exist in more than two options. There are 6 different ways that chromosomes can combine (X, XX, XXY, XY, XYY, and XXXY) that create various different kinds of humans and most people never have their chromosomes tested so using this as the basis for your gender is ridiculous. And various other changes in development mean that regardless of genetics, genital variation is nearly infinite.
But even putting intersex people aside for a moment, let’s talk about how useless the term biological sex is when you are dealing with reality. Many trans people such as myself have known from an early age that our brains are different. Long before I ever knew the term transgender or nonbinary, I thought that I didn’t fit in because I didn’t have a boys brain. And more and more evidence suggests that the brain can develop in utero in ways that more closely match the gender identity that child eventually expresses than the gender they are assumed to be based on external signs (although even that research is hopelessly binary). Though huge disclaimer here because there is no one way to be trans. Not everyone knew they were different from birth and not all trans people experience things like dysphoria.
Ok, so say you put aside natural variation in genitals AND you ignore differences in brains. Well I hate to break it to you folks, but the differences continue to be useless. Trans people do not all experience socialization the same way or come out at the same age so there is no point at which you can make a valid argument that we are somehow “essentially male” or some such bullshit. And there are MANY different kinds of gender confirmation surgeries that make trans bodies infinitely variable and often indistinguishable from their gender.
So what’s the point of this? It means that you should stop using terms like “female bodied” or lumping people together based on binary genital arrangements. And you should stop saying things like “all women are” and reducing your research to binary sex results. Yes, statistically there are vast swatches of people who never have cause to question their gender or assumed sex. And you could do your research based on those people and ignore the tails of those statistical curves. But you are missing out on some of the most amazing parts of human experience when you do so. I am here to tell you that the conversations that happen among trans and nonbinary people behind closed doors that cis people rarely get to experience would blow your mind! And because of constructs like “biological sex”, many of these people intentionally avoid revealing that complexity to cis people and often rule out dating or interacting with you altogether.
So if you want to benefit from what we could bring to the conversation, think deeply about how you can be more inclusive and the assumptions you make on a daily basis. We are here and we are so much more queer than you could possibly imagine.