I simply look at basic biology and how species have evolved from the simplest forms. Of course, gender exists. It's the way procreation has occurred and there are definitely gender differences. If there weren't, then trans people wouldn't be getting hormone treatments and surgical procedures. The current trans mania is more psychological in my opinion though gender "roles" are socially created. There is a physical difference between genders. It's basic to all biology. Why people are born as one sex and feel they are another, I think is very complex but also not common. Its recent increase could in my opinion have something to do with the way technology (pollution, toxic chemicals, etc) is changing the environment and our species adaptation to it. For instance, human sperm counts have been progressively declining in the last 50 years. Why is that?