Empathy is a choice, and can be trained.

I want to pass on some clips from a review by Cameron et al. that summarizes, and has links to, a number of studies that deal our ability to share the experiences of others.

While a single crying child or injured puppy tugs at our heartstrings, large numbers of suffering people, as in epidemics, earthquakes and genocides, do not inspire a comparable reaction...Not only does empathy seem to fail when it is needed most, but it also appears to play favorites. Recent studies have shown that our empathy is dampened or constrained when it comes to people of different races, nationalities or creeds. These results suggest that empathy is a limited resource, like a fossil fuel, which we cannot extend indefinitely or to everyone.

While we concede that the exercise of empathy is, in practice, often far too limited in scope, we dispute the idea that this shortcoming is inherent, a permanent flaw in the emotion itself. Inspired by a competing body of recent research, we believe that empathy is a choice that we make whether to extend ourselves to others...one of us, Daryl Cameron, along with the psychologist Keith Payne, conducted an experiment to see if ...motivational factors could explain why we seem more empathetic to single victims than to large numbers of them.

Participants in this study read about either one or eight child refugees from the Darfur region of Sudan. Half of the participants were led to expect that they would be asked to make a donation to the refugee or refugees, whereas the other half were not. When there was no financial cost involved in feeling empathy, people felt more empathy for the eight children than for the one child, reversing the usual bias. If insensitivity to mass suffering stemmed from an intrinsic limit to empathy, such financial factors shouldn’t have made a difference.

Likewise, in another recent study, the psychologists Karina Schumann, Jamil Zaki and Carol S. Dweck found that when people learned that empathy was a skill that could be improved — as opposed to a fixed personality trait — they engaged in more effort to experience empathy for racial groups other than their own. Empathy for people unlike us can be expanded, it seems, just by modifying our views about empathy.