I was thinking about leadership styles and how to choose one's own style. One of the criteria that comes to my mind is to choose something that we will believe in and something that goes in pair with our inner self. This would mean that based on our past experience and beliefs we can choose what's easiest for us to adapt and practice.
In this way if one finds the style one is closest to then good results should come as well (at least relatively easily). Then I could say that everyone is capable of being a leader, depending on the situation - if it goes in line with the style one practices it should work.
However what determines effective leaders? Referring to the above thoughts, to be an effective leader would require being efficient despite situation. This would require being able to master as many styles as possible. However this number will be limited by ourselves as we would have to be able to adopt different styles holding views we hold. This might be a place for continuous improvement and personal growth/development then.