So, there are some things I want to clarify about casting curses and hexes on people. Yes, if you do cast one on a person WHO DOES NOT DESERVE IT, then it will come right back around and hit you three times as bad. BUT! if you cast on a person WHO DID DO SOMETHING BAD to someone else, then you will be justifying there action, thus no bad will necessarily come your way.
Example 1: If I felt like making someone sick just cause I could, and I curse the person and they didn't do anything to deserve it, then soon I would become 3 times as sick as the person I cursed.
Example 2: If I cast a curse on someone who mugged or beat up another person, and I cast a curse on them to make them very sick, then the person will become ill and no bad would necessarily come my way, because I am justifying his wrong.
Hopes this makes sense.