The idea of "normal" is a statistical affectation. It is an attempt to take a large assemblage of disparate items and find some significant middle to them, that ties them all together into a neat package that can be leveraged to make "value" judgments. It is an imaginary line that runs through each and every grouping imaginable, placed there by outside agency, a wholly artificial yardstick against which each and every thing in the group is measured.
From statistics, the idea of normal has progressed into the realm of human society. When you have a group of numbers representing data points in a continuum, you can use those to find a middle, an average, a norm. Then you can place every number in relation to the norm, leading to "above average" and "below average," and "normal," where something varies very little from the mean. And if that works for numbers, why not people? It starts with physical, measurable characteristics: height, weight, percentage of body fat, age, etc. Gradually, it expands to more ephemeral and esoteric regions: intelligence, beauty, wealth, and the like. Soon, we speak of people only in terms of their relative "value," and just how far from "normal" they stand.
This process of measuring and charting and cataloging humanity can be shown to be the determining factor behind the basest of human interactions: spite, envy, bigotry, racism, snark, superiority, hypocrisy, lack of empathy, judgmentalism. Where some artificial "norm" exists, and where we choose to compare others to it, we set up the conditions for placing people in category we find desirable or undesirable. We reduce human beings to numbers, names, categories, and so on; we place ourselves above others through wholly artificial and self-serving measures. We act as if this is how it is supposed to be.
Over seven billion people inhabit the Earth and the genetic variation between them may be unbelievably small, but it leads to a rich and varied species that has come to dominate the planet like no other. If that seven billion can be reduced to any number, it is one -- one species. The individual variations that appear in each and every one of us are part of a pre-programmed inheritance billions of years old, that drives even a singular species such as ours to display as much diversity as possible, to allow for a greater chance at survival. No measure of such variation can lead to anything that resembles a "normal" human being; we must pursue a varied, divergent, and expanding course in order for humanity to survive.
There is no fractionating humanity. Like the picture that is made up of millions of dots, humanity is a species made up of billions of variations. The drive to create conformity, to place everyone in their box, to hold up some as paragons to be aspired to, is to go contrary to everything that gives our species its strength. Unity of purpose and breadth of vision are far greater reinforcements for our advancement as species, than attempts to anchor us to artificial measures that hold no basis in our evolution. Appreciation of our differences makes us human; anything else makes us mere animals.