This is the title of a provocative book by Todd Rose. He makes a compelling case for the variance among members of any category– whether animal, vegetable or mineral. From the introduction:

In this book, you will learn that just as there is no such thing as average body size, there is no such thing as average talent, average intelligence, or average character. Nor are there average students or average employees—or average brains, for that matter.

His logic rests on math, not ideology about uniqueness. Study after study cited shows that when a set of factors is used to derive an average among items that no specimen is average on more than one factor and most are average on none. This led Rose to speak to the “Jaggedness Principle” to define the weak correlation among factors when arrayed on a continuum.

Now to the merger of beliefs and statistics much later in the book:

But now we know there is no such thing as an average person, and we can see the flaw in the equal access approach to opportunity: if there is no such thing as an average person then there can never be equal opportunity on average. Only equal fit creates equal opportunity.

I think of the old adage “If the shoe fits…” The variation in fit is determined not by the shoe but by where I am going and have opportunity to go.