There is some evidence for the hypothesis that humans have been getting more altruistic since the invention of farming. War deaths per capita have been declining throughout recorded history. Crime is also about 2-3% of what it was in the middle ages. Perhaps the evolutionary stable strategy is one with more empathy?
Even if no selection for a more empathetic genome is taking place, no human trait is solely genetic, and it's certain that environmental factors that increase empathy are more at play in today's developed world than in history. I know childhood malnutrition decreases empathy in adulthood and that's simply because our body is so good at coping with limiting resources and shutting down activities that it can't afford (in this case growing certain parts of the brain).
Conjugal visits are dysgenic when compared to no conjugal visits, but being in prison definitely makes you less likely to reproduce than being free.
If there is a dysgenic problem, I think it will be solved in the next few centuries by biotechnology and designer babies. We've endured 12,000 years of genetic drift since we invented farming, another few centuries won't make much of a difference.