Also, my favorite current teaching tool for the question about why people do bad things is the Harry Potter series, which Molly has now read in its entirety four times. You see a wide range of answers to that question. There are characters who do evil out of fear; out of hunger for power; because they're overly loyal to their own family to the exclusion of all else; from racist beliefs; etc. There are also genuinely good characters who make the wrong choice out of the best intentions.