Being norwegian, I have never been able to identify with this massive guilt towards other ethnicities. My ancestors never enslaved another race, neither in ancient times or more modern (the vikings did keep slaves, though, just usually white ones).
I may be white, but I have never done anything remotely racist in my entire life. Neither has anyone in either my immediate or extended family, past or present, to the best of my knowledge. I do have german ancestors, dating back to the late 1700's, so it's entirely possible that some individuals in the long lost german line of the family were nazis, but that has nothing to do with me.
In short, my conscience is clean.
So should yours be. You have done absolutely nothing wrong, and you are in no way responsible for the actions of those who came before you. How could you?
It's true that europeans (and later americans) have done many terrible, terrible things. But we can't possibly be considered guilty because of that!
I study history at the Uni in Trondheim (NTNU). We had a guest speaker in african history once, an african man named John something or other. He had a very enlightening and to me very new perspective on slavery: Slavery was nothing new to the african tribes the europeans had dealings with. They practiced slavery themselves, and the kings of the regions traded slaves for riches with the european slave merchants. Arabs had taken african slaves for centuries by that point, and even before that slavery was known and a part of the culture of many african peoples.
My point is, the world is a horrible place. Bad stuff has happened, happens and will happen. And we can only influence that in a very limited way as individuals.
You are not to blame for the sins of your fathers. No one is.