Yesterday, I was watching Harry Potter and the Deathly Hallows (part 1), where Harry is wondering whether he knows Dumbledore at all. He knows Dumbledore as a guide, as a leader and as the headmaster of Hogwarts but he doesn't know him as a person. His personal life, his family are all unknown to him.
I think this happens because while growing up we do not see people like our parents or teachers as 'people', we see them under the paradigm of their role. And the idea of them having a life outside of their 'role' is absurd to us at this age. Oprah, in one of her shows, shared a similar incident from her childhood. Once she saw her teacher eating at a restaurant and she was shocked to see that. We, as children, are used to acknowledge people according to the role they play in our lives and thus never perceive them as 'people'. But as we grow up, the other dimension becomes visible and it can be hard at times to undergo this transition. But that is what life is all about, isn't is???