On the contrary, my dear Feign, it requires little effort to know what the norm is. If the vast majority(80% and up) of the population has the same feature, you can very well call it the norm. It isn't hard to say that it isn't normal if a person is extremely vulnerable to UV rays(also known as sun allergy), and it isn't normal to see a natural left handed person in America, because they are both the minority, and a tiny minority at that.