How much control do people have over their personality?

[SvennoJ]

Mr Khan said:
Assuming no variation in mental health or intellectual ability, everyone is going to make the same decisions in the same scenarios. People with psychological problems will make different decisions, as will people at different levels of intellect (mostly because they are better or worse able to fit the scenario into the bigger picture)

The rest of it just comes down to circumstances: how you were raised and where you go with yourself.

Under the exact same conditions maybe, and mostly the same outcome most of the time. However next to determinism I also think chaos theory has an impact on the brain. Just a small variation in the input or your current mental state can sometimes cause a completely different outcome. These one off changes can even be responsible for personality changes together with how the brain reinforces previous behaviour.

Anyway people make different choices with the same mental health and intellectual ability. For example I have been part of a couple of prisoner's dilemma type experiments in economics and pshycology. There wouldn't be much point to these experiments if all the students would make the same decision.