A lot of people don't know that our past experiences can have a big impact on our brains and our future actions, violent or nonviolent. But they actually do, and can depending on genetics, environment, and numerous other factors. Brain damage like the MAO-A gene can affect anyone, but this it is more likely to happen to a male because its carried on the X chromosome and this increases their chances of having it because they only have one X chromosome. However, psychopathic habits won't start to show up, unless something traumatic happens early on in a person's life. Relating this to Perry, he had an extremely traumatizing childhood and it resulted in his violent behavior later on in life. Seeing domestic violence, deaths, and experiencing judgment from those he was supposed to trust did him a great amount of harm. While Dick never really experienced as much trauma as Perry did as a child, the life that he chose to live could of very well encouraged his psychopathic behavior. So even though the MAO-A gene is not someone's fault if they have it, if said traumatic events happen it is unmistakably a recipe for disaster for anyone involved.