If we say it is the behavioral and emotional characteristics of a person, then those things can be visibly changed. You can train yourself to be a more positive thinker. You can become a Christian and your outlook on life changes. You can have negative life experiences such as being a victim of a violent crime or being in a war and it can affect how you react and behave.
So, if we're looking at behaviors and emotional characteristics - I think those things can change. The core of who you are as a person - that I think does not change. What you realize as an individual with respect to that core is something that can be influenced.