Back in my day, Kindergarden was fun and everyone was your friend. Why are there bullies there now?

What factors would cause a 5 year old boy and girl to bully his or her peers in Kindergarden? I'm trying ti understand this, because right now, I'm boiling mad. I left a message for the vice principal, and the heifer hasn't called me back yet. I've spoken to the teacher about 4 times. Everyday, my son comes home with a story about this boy, "Matthew" and this female delinquent "Mary Elaine". Kindergarden. Tell me why? My son will not hit. I want him to fight back though, but it seems not to be in his nature. Do parents of these hellian spawn think this $hit is cute? Kids have DIED from being aulted by bullies at school a href="http://www.bullyonline.org/schoolbully/cases.htm" rel="nofollow"http://www.bullyonline.org/schoolbully/c…/a and after reading up about these things, I want so bad to cause bodily harm to the parents to see how they enjoy it. I have to restrain myself from saying something smart when I see these little bitches at his cl. Yes, I am fed up. What the hell is wrong with these frickin' bad ed little kids?