They say that gender isn't real either. It is socially constructed and the rules are made up, but if you take on some of the stereotypical mannerisms of a woman then you magically are one.
Liberals/progressives/democrats keep saying race isn't real, that it's a social construct not based on science. But yet they're the only ones obsessing over race, judging people based on race, making decisions based on race. Really think about that.