Empathy is an innate quality in humans. It ensures that we have the ability to feel for one another and this further promotes kindness and co-operation. The more people are alike, the more they identify with one another. In fact, it has been found that if you did not identify with a victim of any kind of trauma, you are unlikely to be vicariously traumatised. This may be protective for rescue workers in major disasters or healthcare personnels dealing with patients with PTSD.
In this interesting study on empathy in rats. Watch the video!