I remember I had no empathy as a child. People, especially other children, were not other beings to care about; they were just interesting things to interact with. Animals were about on the same level as people, less interesting to interact with yet easier to control.
When I got a rat the first thing I did was cruel. I grabbed its tiny paws in between my fingertips and held them up above it's head so it had to stand on it's hind legs and couldn't move. At first it was fairly still, but this was a rather uncomfortable position for it to be and soon writhed around trying to escape. Each time it squirmed I jerked it's arms up still higher, only to lower it slightly when it was still. It stopped making large movements, but I kept raising my standard for stillness until even the slightest twitch warranted a cruel jerk.
When it was completely still I decided it wasn't good enough. I had to make it dance. I jerked its arms around so that it had to shuffle its feet. I didn't think it was funny, I just thought it was interesting. I enjoyed it, the more pain the rat was in, the more I got the sick joy of tormenting it.
I never once stopped to question if it were inherently wrong; that is until my mom told me to stop (luckily for me she only got a slight glimpse and thought I was just playing with it). Then I thought it was wrong, or at least it was something I wasn't supposed to do.
I remember another overtly cruel, senseless incident. There was a plant that consisted of long, grass blade like leaves in my friends yard. The blades were somewhat stiff and cracked perfectly as a whip (and hurt just as badly). The other kids just cracked them into the air, seeing how loud the crack could be. Without thinking I cracked it at a girl who was slightly older than me.
I giggled. Crack!
"OUCH!" She ran.
I chased, cracking away. I was so caught in the moment of the joy of hurting this girl that it took my mom several yells of my name before I even realized she was yelling at me. Whoops. I'm not supposed to do that either? I'm "sorry" (a word I never meant until at least the age of 8).
Not only did I hurt others without thinking about it, I ENJOYED hurting others. I didn't understand that this joy should bother me.
I'm glad I am such an introspective person, or I could've been well on my way to much, much, more horrible things. My parents also played a key role. They taught me what I shouldn't do as long they were watching. My logic and internally formed ethics taught me what I shouldn't do when they weren't.
Deep down, I may still be a sadist. I may still have the capacity to enjoy other's pain. We all do. Part of being a child is learning how and why to suppress it.
Either that, or I'm just messed up in the head.