https://youtu.be/nVQplt7Chos

That’s a 90-ish minute video by evolutionary biologist Forrest Valkai goes over the science of sex and gender. The TL/DW version is that the quote here is exactly right. Sex is fuzzy and before you could even start to say something like that it’s binary you first need to establish which of the many sex markers you’re going to use and why you’re excluding the other ones, gender is a social construct which is not the same as sex, and any modern biology textbook above a high-school level will say exactly that. Not implicitly, but explicitly.

If it’s the kind of thing you’re interested in and you’ve got 90 minutes to spare you could do worse than listen to a scientist lay it out.