How tightly integrated are our personalities?

Consider the typical person with a fear of flying in an airplane. Most of these people are conflicted. On the one hand they have a fear of flying and on the other they know that the fear is groundless. Most scientists do not think there is a central brain location for our personalities. They say that contributions come from different areas, yet for the most part, unlike the person with fear of flying, we seem remarkably consistent in our behaviors. How is this possible?