Once again, I feel you’re looking at things in a very simplified manner.
I work in an office full of every creed and colour you can think of, without any division in who gets along with who and there’s no evidence that anyone hangs around with others based on their nationality/religion/colour, in the centre of a city where millions of folk from all sorts of backgrounds get on well without killing or hurting each other.

1) Does that mean that human nature isn’t to gravitate towards those you identify with most? No, that is quite normal.
2) Am I suggesting there aren’t pockets of communities where there is a desire not to mix with the wider community at large? Absolutely not, and that has always been the case even going back to Irish and Commonwealth immigration. But again, we are talking about a minority within a minority.

By your own words, you are telling us you are not tolerant yourself. If other people don’t want to integrate (or worst still, want to hurt those who live differently to them) then replicating that behaviour (as the far right do) is compounding the situation, and the cycle of hatred continues. Surely we all should have one common enemy, that is extremism, whatever the motives and whatever side of the divide these people are on.