Everyone possesses an innate desire to be around people they feel most comfortable with. Usually these are people that display similar physical, mental and behavioral characteristics. To seek out like minded and/or similar looking people is a naturally developed survival instinct.
This only really becomes a problem when that same instinct becomes a cult of ignorance where the cult minded tribalist seeks power over other groups either by claiming superiority through supremacy or by claiming inferiority through victimhood. Either way, it's an attempt at grabbing power and control over others.