Nature vs Nurture

So I had a dentist appointment today and my good friend Marlene watched the kids so I could go. I was having a busy day with lots of work at home in the morning (still recuperating from camping) and rushing to this appointment. I get back to her house and her daughter Stephanie was crying like she had been hurt. Thomas had just finished wacking her with a metal pole. Poor Marlene blames herself for having the pole out! Of course, Thomas is tired and he gets himself in trouble when that happens. What's a mom to do? We apologized and decided we won't do that next time (how many times have I heard that one?). I can't tell you how many times I have said no hitting, please listen to me, be nice to your friends, ... And I'm as nonviolent and noncompetitive as they come. But I tell you, Thomas definately pushes the envelope with me. He teaches me constantly what it is to be patient and non-impulsive, things he still has yet to grasp. And Chris is laid back and calm, while Thomas is all about the drama. Thomas impresses me with his ability to laugh when being yelled at and defying for the fun of it; these ideas never occurred to me when I was little, Miss Goody-goody. So are we as parents at fault? Is the nurture part of the arguement to blame? Or is it his nature and personality, things we can't really control? As a matter of fact, the more I do try to be strict and control him, the worse it is. Having a "home-grown" child and an adopted one does make me think a lot more about the nature vs. nurture debate, especially because they are so different. Of course, Thomas is only 3 and I just keep hoping these challenging traits will serve him well as an adult. In the end, he is an adorable, intelligent, little imp that I love to pieces. Even when I do yell at him and have bad parent moments at times, I hope he always knows that.