Describe personality development.
The question posed in most child development classes is what affects personality development more, the child's genetic composition (nature) or the environment in which the child is raised (nurture). I used to be fully on the side of nurture. I believed that with the right system of rewards and consequences, any human could be made to do pretty much anything.
Then I had children of my own.
I'm now about 90% on the side of nature when it comes to personality. Kids are born with the personality they have - I am convinced - and environment/rearing/rewards/conseqences can only train them into using their powers for good and not evil.
I say this because both of my children displayed prominent personality traits when they were only 4-6 weeks old. Stubbornness, or laid-back-ness, or patience, just temperment, generally, cannot be altered much by environment. Now I believe that if a child has an extreme and unpleasant personality trait, it is just a matter of consistency to teach them to stay within certain behavioral boundaries - but I think the personality trait will always make this a personal battle - for both the child and the caregivers.