God hard wired us with some learning programming. They discovered that when we watch certain individuals, especially in our close circles, we neurologically experience the same thing they do. By sticking electrodes in the brains of monkeys they saw that when the monkeys watched other monkeys eat, or whatever it fired the same corresponding neurons in their own brains. They called them mirror neurons. The reaction was more prevalent among closely related primates, like parents and offspring or younger to older but less older to younger. This makes perfect sense when you look at the how we react when we see somebody get their hand burnt, we wince. When a child scores a goal, or misses the goal, the parent reacts accordingly. The conclusions can be drawn that we learn from those close to us, and in authority, but not subordinate. If we see someone as less of an authority we have less of learning connectivity. This is empathy.
Also the brain is always trying to seek balance. If it experiences too much excitement or not enough, it adjusts. It "throttles" the receptors accordingly. If you present too much excitement to your brain with chemicals like cocaine or video games it causes your brain to become less receptive to excitement. This results in depression and you have to continually increase the excitement until the point where no excitement is enough, enter depression. The opposite is true as well. If you have a crappy life and nothing to do, your brain will adapt and cause excitement with very little. Many stand up comedians came from impoverished, or abusive circumstances. It's God's way of allowing us to be happy with less.
There is direct relation with things like watching movies but to cut through the chase, our brain adapts to experience. If we experience continual, physical and emotional trauma, our brain disconnects from emotion. Then you get sociopathic behaviour. I think that these people are so starving for any form of emotion that they turn to causing the extreme pain of others to get just a tingle for themselves. Narcissistic behaviour I believe is the result from having one parent that has nothing but praise and the other who has nothing but criticism. This leaves the individual with extreme insecurities, protected by outer self who is seemingly accomplished. They work hard to keep up appearances. If there is any challenge to this facade, the individual will lash out to any degree to conceal the weak, fallible self. These people look like they have it all together, and seek controllable mates. They look like perfect parents then in private become abusive.