David DeSteno, PhD, writing in "The Calculus of Compassion: What determines whether we feel another's pain?" says,

This and related findings clearly demonstrate that the capacity for compassion, and indeed our characters in general, are not fixed, but are determined dynamically moment-to-moment outside of our awareness in an attempt to balance the pressures of social living. At first, this may seem dispiriting, but in actuality it can be liberating. In the end, each of us has the potential to be not only a sinner, but also a saint. 

• Can you identify how compassion arises within you?
• Are there specific practices that help you cultivate compassion?
• Who inspires you during this time of your life?

Full story: Psychology Today, May 11, 2011, "The Calculus of Compassion: What determines whether we feel another's pain?" David DeSteno, PhD