There is no deny that each person has his/her own personality. Even if people have similar characteristics in their personalities, you just cannot classify them in categories. In my opinion a personality is more than what we can understand.
People develop personalities due to their families, cultures, life style, environment, school, even pocket money in their childhood. Everything influences a personality, many are aware of that, others not. The interesting part is that if you are more aware of how an experience can change your personality you can actually do it.
I like to believe that we do not grow but our personality grows, becomes more defined, with a million of possibilities, and so complicated, so many aspects to look at, so interesting. This might increase the level of being egocentric, but at the end of the day, is not bad having defects in your personality, its normal and its better when you know how to turn them into qualities. There is no doubt that some defects can be used as qualities; and vice versa, I will not give examples because I prefer not categorizing which is a defect and which is a quality; Each one can see these features of a personality differently.
A personality can never be known entirely and no psychological test can precisely define ones personality, not even I know completely who I am and what I can be capable of.