Difference of opinion is what usually starts it. Not everyone is going to get along with everyone. I try my best to not take sides in matters, it's kind of a cowards way out but I try to avoid confrontation at any level. I avoided fighting throughout my life, many people wanted to mess with me but I just "turned the other cheek" to see how they would react and they just stopped. Fighting is part of a base primitive emotion brought on by fear. When someone's beliefs or livelyhood are threatened they feel the need to show dominance on any level. Be it against a neighbor, family, animals or their dick.