Well racism is the backbone of a lot of problems facing the world today. It's a big deal and I think knowing what makes people feel their race is better than others can be traced to two things.

1) parentage: in a family, children tend to emulate their parents. They have no idea how they should act in certain situations and so copy what their parents do. It's very common to see kids making the same hand gestures as their parents or walking the same way. But it's not only positive things children learn. If a man or woman are racist and they openly display their disdain for other races in front of their children, then the kids will also become racist. They will have no idea that the hatred they feel for the other races is wrong and by the time they get to an age where people notice and try to correct them, it will be a founding part of their personality and as such will be hard to change.

2) some people believe that they are perfect. They believe that anything that varies from them is wrong and beneath them. This belief is also a foundation of racism. No person is better than the other. We are all equal but some believe that their skin colour or country of origin or hair colour is what should be and everything else is wrong. So once you do not conform to their standards, then you are below them and they are better than you. These are where the white supremacists fall under.