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.
Labeling something does not make it a ‘social construct’.
We label rocks based on how and when they were formed. This does not mean it has any sociology behind it.
But I do respect your opinion and if you do think so, you are well within your rights to do it.