Touchy subjects arouse emotion. People in civil society usually try to overlook the differences but in fact do not. Their attempt to cover up noticed differences sometimes fail, hurting others. Social and cultural differences can be a source of feeling and high drama, essential to effective writing. Differences can be in clothing, choice of words, habits, mannerisms, and much else useful in both characterization and plotting.
Eccentricity is valuable to writers because it interests readers.
In reviewing the important novels of the century, it is clear that almost all of the protagonists are eccentric. The everyman hero or heroine does not please readers who long to spend twelve hours with characters more interesting than and different from the people they meet daily in shops and streets. In short, give each character a different script. In life, in any group of two or more people, each is functioning with at least somewhat different experiences and intentions. I first saw this technique used at the Actors Studio to train playwrights.