It's probably genetic to be honest. I mean, if all the members in a family had the same personality, they would all want the same things and probably end up falling out with each other. If we all have different preferences and want different things, then it avoids conflicts, so, in this respect, it's innate. But our personality is also affected by the life experiences we have. If one brother has a traumatic experience that his sister doesn't have, then this will have an effect on his personality and possibly change it.
It's probably genetic to be honest. I mean, if all the members in a family had the same personality, they would all want the same things and probably end up falling out with each other. If we all have different preferences and want different things, then it avoids conflicts, so, in this respect, it's innate. But our personality is also affected by the life experiences we have. If one brother has a traumatic experience that his sister doesn't have, then this will have an effect on his personality and possibly change it.