Everyone Wonders Different Things

I thik that we all have different things that we question in the world. From why people hate eachother for a reason of color, to why people feel the need to kill others. My question is why others have to hate. I just don't understand how you can hold all of one race responsible for what just one person has done. It's like you group everyone into one group. It's just like when women were unable to work. It was the oppression of an entire group based on the facts of gender. It has gotten better but in many cases it still happens. So how does it stop?