Whatever the balance between nature and nurture, this phrase has some provenance.
Whether it's from the song made famous by Shirley Bassey and then most recently John Barrowman ... I am what I am, my own special creation, a notable Popeye phase from the 1930s, and with earlier biblical references too.
We are all different, and that's reflected in every personal interaction, and hence every work interaction too. That's why in the world of work there's a lot of time and effort expended in that understanding of self, as a steeping stone to understanding others.
One of the most popular models of types of us is the Myers-Briggs Type, based on the work of the Karl Jung. Here's my ready reconner that lays this out in a visual way to get a personal sense of where our personal preferences lay.