Authenticity? Hogwash?

 I keep seeing references to authenticity, most recently in this post at Prof. Fea's new website.

I bought a book on children and essentialism, The Essential Child, a few weeks ago.  The thesis intrigued me, so I went for a used copy (it's older).  As I understand the book, which I've yet to read, a stage in children's thinking is the idea that there's an essential quality to some categories, that it's part of how children learn. 

Seems there might be a relationship to the idea of "authenticity", that there's some essential "you" which you have to find and express.  That might also tie to the recent emphasis on "identity", particularly in the LGBT realm.

At least today IMHO this is all overdone.  What I've learned from my life is that human's are more flexible and adaptable than we often think.  Even people as rigid and order-loving as me can and do adapt.  Who we are is a combination of our heredity, as contained in our genes; our environment; and our experiences.  It's mistake to overemphasize one of the three.