What makes people so evil?

First of all, I know theres probably worser off people out there than me but just hear me out and let me know what you think. All my life theres been nasty people around trying to make things tough for me and my dad. My mom went to blackpool and got engaged to another bloke while still married to my dad. She then burns all our stuff and runs of with her fancy man to get married. She disappears for 10 years, comes back to say hello for 10 minutes and now shes living miles away and has currently married another 3 blokes since she walked out on us. But theres always been my brothers and their girlfriends to make things tough too. My brother would rob off me to feed his alchoholic cigarette munching girlfriends needs and just hurl abuse at me. They still do but I just ignore it all. And my half brother came in drunk and set about my dad. Broke the bones in his hand, kicked all his head and kicked some teeth out. Now theyve all joined together into one big hate club constantly plotting.