Yeah, I think part of that mental capacity and open-mindedness is the innate quality I was getting at that makes people in my observation, better leaders. I've seen people who went to courses and took positions with the interest of genuinely wanting to be better leaders, and have come out exactly that.
I agree with you as well about the life experience having some influence, but using someone like General Abizaid as an example (if you haven't heard of him, you should have a google of him, he was quite interesting), I don't think you can impart the innate 'vision' qualities of leadership. He did a fair bit in transforming West Point's culture and was supposedly a well adaptable leader who could transition through several styles very easily. I don't think you can teach someone to do that and have those visions about how they want their organization to look.
I've seen many people who are appointed to leadership positions, in school, for example, who are given a Captaincy and simply perform the day to day tasks, look neat, and occasionally voice their opinions on design committees. A definition for leadership I was given once at an out of school course on it went something along the lines of 'Motivating a group to achieve a goal'. I think the first part, the motivating, you can teach someone. The goal, or the vision, beyond a certain point isn't something you can teach someone.