The identity that matters most is one's identity as a human-being-becoming-a-person. We can be grouped into pairs, families, clans, tribes, interest groups, nations, and so forth. — Bitter Crank
Let me kindly spice this. Let´s say that I completely disagree with you, in a rational way. People get married to trees, so it kind of confuses me and my notion of person (who can be grouped?). Will my disagreement bother you in great manner? Do you think I have a point here? Or the natural rush you feel against my disagreement will impel you to illogical and nonsensical fallacies?
I know that this questions seem barely relevant, but the way mankind constructs it´s range of acceptances (and it travels real fast in our days!!) appear to me very decisively in the selectivity of futures generations of mankind.
And it also goes the other way: did you know that companies (and even states!) have quotes for hiring people according their race or creed, even if they (like you said) "group" themselves with people that are not the best fitted to perform the tasks they should? All of this in the name of "resolving and annihilating differences" - it is political correct to think so.
Imagine that we have a Savannah, and four lions. But only two gazelles. Imagine now that the lion community decides that lions with only 3 legs should also be entitled to eat a gazelle (in the name of equal opportunities and for the greater good). So, from the 4 lions, 2 lions with four legs will starve and will not have cubs, and the next generation of lions will, probably, have a higher number of lions with 3 legs. You see where it´s going. Can it happen that one day no lion can catch a gazelle? Is it extinction a possibility?
Now, think about today and how we humans are organizing our social environment, and how are we compelled to be flawless in doing the morally correct things.
Going back to the start (what a twist), you can political influence others to completely disagree with me (or because I´m wrong or because you, personally, can´t face the fact that you are less right than me), and in fernesin of constructed set of rules for good and evil (morality) set me apart and ensure that, in the long run, that my genes are not to be passed on.
I´m 40 years old (probably older than all of you), and what I perceive is that we humans, both individually and socially, are getting much more sensitivity to differences. And also overreacting to their existence.
I think this is not a such unimportant subject as you might think. And, off course, I state this with most respect and zero intention to offend.
(just the cherry: personal provocation by opposite ideas between great minds has, historically, given birth to important conclusions and added up knowledge).