One way to think of it is, just about anything one can measure about people tends to fit on something like a bell curve, and those curves are related in way re'anging from nearly totally correlated to nearly not at all correlated. People who are more 'normal' are those who sit closer to the middle of more of those distributions. This isn't normative (what should be) just descriptive. (definition)
Looking at the normative structures around this though, becomes a bit fraught at times. A certain amount of regression to the mean helps social cohesion, as you are less likely to have large conflicts if everyone can agree on certain basic facts, principles, and objectives, but too much adherence suppresses innovation and can turn minorities into enemies, which in turn increases conflict and weakens the whole. Where society settles in the spectrum between xenophobic conformist extremism and radical lowercase l libertarianism is one of the fundamental arguments present in every society, everywhere, and in every time.