That's a very interesting question, but unfortunately it's not really my area. If you'll permit me to speculate a bit: I do clinical work as well, and I'd say

That's a very interesting question, but unfortunately it's not really my area. If you'll permit me to speculate a bit: I do clinical work as well, and I'd say that therapy produces some personality change if done long enough, but it's not a massive shift in most cases, though even small changes can make a big difference over time. Unfortunately, trauma and hardship can also have a big impact on people's personality and average behavior. Going to war or prison or suffering great loss can have a big impact.