It is the fabric of our very existence it is what defines us as a human being. It is what helps us to distinguish right from wrong. At least most of the time that is how things are supposes to work. When things go terrible and we cannot figure out what is wrong with this person we choose to blame it on someone else even the parents. We have a decision to make whether right or wrong. God gives us the freedom to choose what we want to do. If god chose to take that away from us, we would be robots.
Ever since the fall of Adam and eve we have been sinners you may have a different opinion about this but I fully believe we are predestined for a specific purpose from the beginning of the world. Even people commit heinous acts good can still come out of the situation. I am not saying that it is ok for someone to hurt someone else but that is there choice and ultimately good will come out of it even if at that time it seems like it is hopeless. I guess the truth is god has a predestined plan for you since the beginning of the world like it or not live with it and use it to your advantage.