my personal life

Why do children fight? I always fought with my brother. I have a 3 year old son and 11 year old son and a 14 year old daughter. Today my 14 year old got mad at my 3 year old for drawing on her nightstand with a permanent marker then my 11 year old and 14 year old are fighting and arguing about what color the sun is or something they fight about everything. then the 11 year old could not take 30 minutes of his very important and busy schedule of watching tv to play with the 3 year old. I always thought if I became a pastor my children would automaticly be loving wonderful children that never fought. I am an idiot. You where thinking it! I love my wife and my children more than anything in the world but sometimes i wish they came with a manual or at least web support. life is normal. God change our normal!