I think this needs some work.

"When you look at a person of any other race besides caucasian and decide that you know exactly the sort of life they live."

"When you look at a person not of your race or gender and decide that you know exactly the sort of life they live."

You original sentence was racist and sexist. I don't even imagine I know what sort of life other Old White Men live just by looking at them. Just because someone looks like me does not mean they live like me.

TEK