I will say that the idea of a woman being deceptive came from that original discussion with critics and reporters about if woman could do that kind of thing. Evelyn, herself, grew out of the discussions about how capable women are of deceit and lying and manipulation.
Children, if they haven't been introduced to foods by the time they're 3 years old, are afraid of it, as if it would hurt them. They don't really get out of that until they're 6 or 7 - it's a safety mechanism, and you're not going to win.
Jim Thompson understood something about the serial killer before the psychology caught up to it, which is that they are detached to it and they do want to get caught.