Nature vs Nurture?
I believe circumstance brings out the nature in people, whether that be instinct or through chemistry such as the affects of adrenaline. I believe nurture helps people cope with and suppress our nature.
We as humans in society are constantly being told how to act and what to do. We are conditioned to "fit in" with what place or role we have in society. In martial arts we are told how to punch, how to stand, how to breath...
Sure you can force a person into a life or death circumstance, and this can bring out their true nature. However, if they survive that situation, then how they deal with it after the fact is very important. Nurture is what helps them cope with what happened and gives them the tools to move forward from there. Nurture is what shields them from bad circumstances.
Nurture and nature are in conflict with each other. When circumstances bring out the nature in us, we often have an internal conflict... hesitate and not know what to do. Our mind says one thing, but our body does something different.
Decisive action comes at those moments when nurture and nature are in agreement -- when there is a lack of internal conflict.
Through such things as hard, sincere training we put ourselves in circumstances that bring out the nature in us and this conflicts with our beliefs and nurture. We try to find a balance where both nature and nurture can work together for a common purpose.
Some find this balance through compassion. Some maybe find it because they aren't quite right in the head and they just don't care what happens to others.
I don't know exactly the answer, but I feel sincere compassion is a virtue.