Races segregate themselves in their living and daily activities. Shit you can see this just every single day with people walking around a city, whites with whites, blacks definitely with blacks. There's some mixing but it's not equal. When they are forced to live together that's when there is tension. You're basically arguing the opposite of reality with regard to cultural integration. The willing segregation of races is an observable science.

Further, mixed race marriages fail at a significantly higher rate than non mixed marriages. This is a scientific fact.