Your character is your answer to that question. Who we really are is determined by the values we choose to hold, by the beliefs and assumptions that define life, work, and relationships. How we act at work, at home, in social situations, or alone is always an expression of what we really believe, what is important to us at the core. The real me resides in my character and shows up in my behavior regardless of what I say is important. Character is about us as individual persons.
Character is personal.
It is always a choice. We choose what is important to us, but most of us do not spend nearly enough time reflecting on the choices we have made or the values we are reinforcing. But that is another topic. Who we are matters because it shapes our leadership. We lead out of our beliefs and values, our assumptions and commitments.