The always-perceptive Theodore Dalyrymple has some interesting things to say about the question of what causes people to be good.

More recently, perhaps on account of my advancing age, the problem of good has begun to preoccupy me. How is extraordinary goodness possible? Where does it come from? Is it innate? And if it is innate, is it real goodness? For there cannot be real goodness where the possibility and temptation to its reverse is not present.