Its a proven fact that if you don't use it you lose it. Your brain is constantly rewriting your memories, and information gets lost over time. This is why police get police reports ASAP, because its the most accurate account of the person before the mind begins trying to fill in the blanks with guess work.
Believe me man, you do forget things. You're personality allows you to solve problems with experiences you have, weather its the experience of learning others experience (reading books) or actually getting out and doing something. In essence, its a hacker personality. When there is something blocking you, you find a way around it using every available resource you have.
I think it's also proven that you loose things that you understand and/or care about much slower than others.
About rewriting memories... You do not only fill the blanks in your memories. Your brain also fills the blanks in what you are looking at, the exact moment you are looking at it.
