Beyond XX and XY: The Extraordinary Complexity of Sex Determination
scientificamerican.com
I believe the problem is never showing evidence, but that the evidence is overwhelming. I could explain the general idea and, maybe, one or two specifics. People that use the XX/XY binary argument wouldn’t be able to explain either, but it’s usually only used because it conforms to a bias. And we are only talking about humans here. Language would implode if we tried to maintain convenient binaries and still back it up with science.
Say it with me now: Sex is a social construct.
A 'convenient' fitting into boxes usually two, but accurately not always.
The problem with such a system is that it's limiting and not at all useful in trying to help people.
We should be specific in what we are trying to say, because the miasma of a sex binary isn't useful, even in medical fields as it conditions doctors to think in very limiting ways and not actually help accurately.
It also has many roots in patriarchal violence in determining what a person (though to them a body) is for.
It's also problematic in a racist sense because of the colonialist white 'western' ideas of what makes a certain sex or gender often don't fit those who aren't in those categories (except colonised).
Which is why the 'science' is very problematic in this regard because that is the bias/lens with which it looks at this specific 'field' through.
Sex is not a social construct. Gender is.
It's true - we are learning more about sex every year and understanding it's not completely binary. But your sex is assigned at conception.
That's one of the reasons doctor's don't ask about your gender, but your sex - because treating could be different. And, as an example, IHE (medical standard) recognizes about 7 sexes.
Gender, on the other hand, defines social norms we expect from certain sex. How gender is perceived changes from culture to culture and from one period of history to another - sex doesn't.
That being said, I do believe that gender roles should be a thing of the past. You do you, whatever you're comfortable with.
The concept of a rigid biological sex binary is a social construct, that's basically the entire point of this post.
So where do we draw the line in sports?
We draw the line by weight classes and/or muscle mass, not by what's in person's pants. It doesn't have to be just 2 categories or the same categories for every sport, either.