There are, as you know, some people for whom human-ness is absolute. They willing to accept that there are short people, and tall people. They get the idea that there can be a taller-than-average populations, and in those cases, who is short or tall becomes relative. These people get that there are a zillion different skin tones, from albino white to darkest black, and that people are not monochromatic. They accept that hair color varies wildly; that eyes can be different colors and shades, that breasts can be small or large, or anywhere in between, that people vary in weight and in so many other ways. Some of these people even accept that sexuality can vary. Some people are gay, some aren't, some oscillate and some have a preference but can go either way.
And then there are the gender absolutists.
These people get angry when it's suggested that gender can be just as diverse, just as varied as any other aspect of being human.
PS It seems to make them very angry all the time. Which isn't good for their health, so they all have heart attacks from the stress and die after living short, angry lives. Which is a pity, really. Especially when you consider that they seem to be replaced as fast as they pop their clogs.