This is a classic case of the harm that not lying to your children can cause. The things my parents told me when I was young shaped a large part of my world view. If you were a racist, enough of that would seep through to influence your child. If you tried to explain bell curves and so on, and you believed that white people were more clever than black people, your child would grasp the subtext of what you are saying.

The best thing to do is to not pre-infect your child with your own personal notions on controversial topics till he is equipped to think independently about them.