Is prejudice ingrained in humans?

I read this quote today:

"If we were to wake up some morning and find that everyone was the same race, creed and color, we would find some other cause for prejudice by noon."
- George Aiken

Sadly, I see the truth in it. People always tend to find some reason to say that their small group is better than some other group. Even when all the people appear to be the same. Europe or Africa are prime examples. They all have similar physical appearance, especially countries very near to each other, yet, they always find a reason to hate each other.

I often wonder if this is intentionally promoted by those in power. This would be done for want of power. Each group has a leader and most leaders want to be in control of ever more, either territory, people, or wealth. If the groups in the next country is equal, that implies that it is fine for that leader to be in control. If the other groups is inferior, it gives a leader an excuse to conquer so they can "help the lesser people".

There are other places where prejudicial distinctions are made. Think about the grade school yard. Kids are notorious for discriminating. I don't think kids get to second grade without having very defined groups. Some people are able to move between groups, but in general, once a kid is labeled as a member of one group, that is how everyone will see them. Some of this is self selection based on dress, hair style, etc., but some is by association or behavior.

What will it take for humans to just see another human without having preconceived notions about what kind of person they are? Or at least to accept the person as they are (minus those that may do us harm)?