Coming from a multi-cultural family and having studied cross-cultural communications, I always thought if people got close enough they would appreciate their differences. Friends and then relatives from different countries can really move us closer to a much higher level of acceptance.
Finally, here's living proof from Facebook. The "peace page" tracks friendships among people from nations who have been in historical conflict. You can watch it in real time, as people connect on Facebook.
Then, there is the survey across nations. Question is whether you believe world peace is achievable. Americans are most pessimistic. Columbians are most optimistic. I guess being exposed to war news is depressing, and making strides against FARC boosts morale!