There is much disagreement as to whether psychopathy is a function of neurological factors or the result of some aspect of environment.
A study of 1,000 boys in New Zealand found a version of a gene that is linked with antisocial behaviour but that only appears to lead to criminality when its possessor is raised in an abusive environment. While this particular interaction provides a basis for criminality but not necessarily psychopathy, it does illustrate the importance of both nature and nurture in the expression of personality. Evidence suggests that nature, or heredity, accounts for approximately 50% of the expression of psychopathic traits, and environment the remainder.
Nature
There is evidence that psychopathy is to some degree a heritable neurological problem. Studies have shown that:
- Psychopaths don’t have the same physiological responses to fear that constrain the behaviour of normal people, such as rapid heartbeat, sweating, dry mouth, trembling and muscle tension.
- Psychopaths don’t have physiological responses to emotionally charged words such as “love” and “death” the way regular people do, suggesting that they process emotional stimuli differently.
- When one identical twin is psychopathic, the other is more likely to be psychopathic than those in the general population.
- Adoption studies indicate that children can inherit psychopathic traits from a psychopathic parent even when they are raised by different parents.
- When compared to non-psychopaths, differences have been found in a number of brain chemicals among psychopaths.
Nurture
It is now well-known that those who are abused and traumatized in childhood are more inclined to abuse others in adulthood. Unfortunately, this has made it easier for psychopaths to do what they do best—play on the sympathies of others—by claiming to have suffered abusive childhoods. But psychopaths are just as likely to have come from loving, nurturing homes as from abusive ones, and many abused children do not grow up to be psychopaths.
Although abuse can worsen existing psychopathic traits, it does not cause psychopathy. However, it can shape the way in which this personality disorder manifests. A psychopath raised in a loving home is more inclined to become a shady businessman, a romantic user or a nonviolent criminal, whereas one raised in a violent, neglectful home is more likely to become a violent criminal.
Children who suffer from a lack of attachment due to early deprivation and neglect often exhibit symptoms similar to those of the psychopath including law breaking and cruelty. However, they can be distinguished by a propensity for psychological distress, anxiety and low self-esteem, in contrast to the psychopath who has a high opinion of himself and is not inclined to suffer from anything other than frustrated desires. Also, while psychopaths usually work hard at appearing normal in order to manipulate people, those with attachment disorder are more likely to be chronically hostile and off-putting, swinging between belligerence and desperate neediness rather than exhibiting the surface charm of the psychopath. Additionally, the majority of psychopaths do not suffer severe early childhood deprivation.
Social Forces
Many criminologists and sociologists believe that psychopathy is caused entirely by social forces, which include not only childhood home life but also the broader social environment. There is some support for this theory in the fact that certain cultures have a higher incidence of psychopathy than others. Places such as the United States where the incidence is as high as 4% and increasing steadily ascribe to an individualist, self-promoting ethic, whereas places where the incidence is just 0.03-0.14%, such as Japan and China, favour an ethos of connectedness and personal responsibility.
Psychopaths exist in all cultures, even the relatively isolated Inuit, who view them as irredeemable and have traditionally dealt with them by shoving them off ice flows. It is possible that a similar percentage of people are born with the innate tendency for psychopathy in every culture. However, in some places all elements of the social environment strongly discourage the expression of the associated behavioural traits. In other words, being a psychopath is more likely to pay off in America than it is in Japan, so the uglier traits are more inclined to be expressed in one place and suppressed in another.
Evolution and Natural Selection
There are two potential strategies for getting genetic material into the next generation. The first is to have few children and take very good care of them in the hope that they will survive to reproduce. A second strategy is to have as many children as possible in the hope that even if you don’t care for them, at least some will survive into adulthood. Psychopaths follow the second strategy.
Psychopaths are notoriously irresponsible when it comes to birth control. They also tend to be sexually promiscuous, and to abandon lovers and families regularly when they move onto the next conquest. Though they tend to have many children, most don’t take care of them, and those that do often abuse them in some way. Even if their children die through neglect (which is particularly common among psychopathic mothers), they are likely to have more. Diane Downs, killer of her own children, worked as a surrogate mother. Another female psychopath said chillingly, “I can always have another,” after one of her lovers beat her young daughter to death.
Brain Damage
Some individuals who sustain damage to the frontal lobes exhibit behavioural similarities to psychopaths, such as poor long-term planning, shallow affect, aggressiveness, low tolerance for frustration and impulsivity. However, research has not found brain damage in diagnosed psychopaths.
Further Reading
For a comprehensive list of references on psychopathic personality disorder, visit Dr. Robert Hare’s website. For more information on psychopathy, see Personality Traits of a Psychopath, Behavioural Traits of Psychopaths and How Psychopaths Exploit Others.
References:
- Nature via Nurture by Matt Ridley
- The Sociopath Next Door by Martha Stout, PhD
- Without Conscience: The Disturbing World of the Psychopaths Among Us by Dr. Robert D. Hare
