Demolition Derby!

At times, some things can make me wonder...
One such time was this summer when we went to the Demolition Derby with the whole Christensen clan plus a few. Ok. Here's the thing...I really loved it! We had so much fun yelling at these cars that were completely trying to obliterate the others in the ring. We would start betting on which ones would win--calling which car was "ours" when they paraded across before the chaos ensued. Then, when the buzzer rang and the smashing began...forget it...alter egos came out!
This was apparent when I looked down at a family friend whom we had invited, along with her five year old son. She had a look of horror on her face as she desperately tried to shield her son from being permanently scarred from the real life violence unfolding before her. She would interject questions about if people could die, or how much they could benefit from a good chiropractor, and what not. She ended up leaving early...probably to reevaluate her friendship with such a primitive group.
Good thing she left early, because the BEST was when the gals got into the cars! One even rolled over the top of another car, completely flipping it on it's top! She was just fine, but we were a bit disappointed when the ambulance blocked our view of the rescue--they even got out the jaws of life.
Now what's not to like about that kind of entertainment?
So, is it nature or nurture? And do I have some mysterious redneck bloodline??