An infinite number of factors go into developing a personality, this covers a lot of the big ones.
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Lately I've been thinking about the windows of plasticity and why people change beliefs as adults.
The sad fact is that a lot of people have a lot of very wrong and bad beliefs, and unfortunately most of them are already adults, so you don't get to discipline those beliefs out of them (I hope you can read this as tongue in cheek); You will never get mad enough at a person to fix them. Anger is motivating, but you don't get to pick the direction.
As I understand it, psychologists believe that parents and the environment of a person's youth set a lot of their basic beliefs about the world, but it is their friendships in adulthood that most determine their value system - you want what is best for your friends (and yourself).
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To me this also ties into evaluating the actions of historical figures; people seem to get hung up on very flat depictions - was it ok that a person who did good things also did bad things? Well, they are a whole-ass person, raised in a different time and place. They didn't choose when and where and by whomst they were raised. They had some level of choice in their friend group, but that is also constrained by time and place.
I feel that you can judge people and actions, while also allowing space for humanity and personal stories; but that does take a lot of time and emotional work. It is much easier to just choose one side of the coin or the other, face or heel.