I'll give you an example. Let's say that you were from my world, and you were born in the Britannian Empire. That means that all your life you would have been taught by your parents and your teachers that the people the empire conquers--they called them the "numbers"--were inferior to you. Some people are able to break out of that kind of thinking, but most Britannians just lived their lives thinking that they were a superior kind of person, and that it was only natural to hate the numbers because they were a lesser people.

So, do you get what I'm saying? Hating someone on principal means you have that hate engrained into you. It's a pretty horrible thing.