One of the problems we face is that maximum physical differences among people coincide with maximum conformity instincts at the same chronological age (i.e., teenagers), which is compounded by sexual and other social complexities. Same sex schools, although politically incorrect, can mitigate this problem, especially if uniforms are required. It is too bad that teachers unions are among the most vocal opponents of this approach.
Pretty sure racism exists in countries with gender separation and school uniforms.

Racism's a global phenomenae and not easy to nail down the most responsible contributing factors. Even in monoethnic cultures like Africa you get ethnic bias and conflict with all-black groups persecuting minority ethnicities from different tribes and traditions and the like. Seems like we always manage to find something to persecute others for be it skin color, ethnicity, religious affiliation, tribe, etc. Even Native Americans before European invasion warred with each other.
Place to start though as ever, is education and communications. With internet, cable tv, and the ability to see how other people live in other locales, anything that doesn't ring true will be found out. I think we're doing ok in the US though. Have yet to hear anything from the kids around here amounting to racist rhetoric or bias. Was struck recently when some of the kids referenced my being bisexual (which I'd thought I'd kept under wraps pretty well) trying to fix me up with some guy. More surprising than the revelation I'm evidently 'out' was these kids don't have the problems with it we did when their age a generation ago. Gives me hope.