this is a hugely important element of the human psyche -- there's a lot of tribalism in all of us -- we all enjoy a small group with which we can closely identify -- the problem is that the natural tendency is then to marginalize those outside the group (thinking of them as not as "close" or "deserving" as the close group of friends/family is) -- i think it's not far-fetched to think that talking about this and educating people about the "emotional" weight this carries (as it's definitely an evolutionally selected trait) can perhaps eventually overcome this source of societal friction