First, why do you seem to be associating culture and race? Do you realize those are, in fact, completely independent things, and one's race truly doesn't tell you anything about one's culture?
But maybe I misunderstood you there, so I'll give you the benefit of the doubt.
Second, "There is no Culture"?!?!?!?!
That I can't give you the benefit of the doubt on. That is clearly one of the most insane things I ever read.
Culture is an integral part of one's identity. Like it or not, most people, especially kids, are EXTREMELY prone to influence and mob mentality. Kids will look up to their parents, and/or to external role models, and try to be like them. That is part of the process of growing up. Even "worse", kids who will go against that, and try to swim against the current, will be quickly attacked and, in many cases, shot down and humiliated.
Things don't change that much when you're an adult -- it's just that you can completely isolate yourself if you're different -- but is that much of a life?
That is the core of the development of a culture, that evolves over time inside communities -- and yes, this is true especially in communities that are purposively isolated or segregated, either by themselves (self-segregation) or by others.
But even if we completely stopped segregation (both types), including racism and class-based segregation, different cultures would still emerge, from all kinds of influences. People would look for cultural guidance anywhere and eventually local cultures would again develop, across racial lines, but they still would. It is just so much a part of humanity that you simply cannot get away from.
It is basically collective thinking, fueled by role models and mob mentality, some of the most fundamental things in humans.
Some excepcional people will break away from it, but very few have the intelligence, the guts and the energy to be "different". And, even the ones that do, in a sense, they will adopt a culture too, albeit a different one from their surrounding community.
Culture is not one of those things that "if you ignore it, it will go away". It is something that was, is and will always be there, and we need to understand and deal with... not to hope it goes away, because it never will -- even if racism does, eventually.