Psychopathy is a cluster of traits that relate to exploiting others. That definition includes two separate factors of psychopathy.
Factor 1 can be defined as the interpersonal factor. It is associated with being glib or superficially charming as well as having a tendency to exploit others. Factor 2 can be defined as being impulsive as well as having a history of frequent and varied criminal behavior. While Factor 1 is often viewed as theoretically more interesting (it’s what most clearly separates psychopaths from most criminals), Factor 2’s inclusion of behavior means that it’s the more predictive of the two factors when it comes to criminal outcomes (Hare & Neuman, 2008).
Psychopathy is the best individual predictor of violent crime and recidivism (recommitting crimes after being released) with psychopaths committing crimes at roughly 2.5 times the rate of average individuals (Gatner et al., 2023). In most Western prison samples, psychopaths make up 25 to 50 percent of the violent offender population. In the United States alone, psychopaths are estimated to cause hundreds of millions of dollars worth of criminal damage (Gatner et al., 2023).
But for any individual who is unlucky enough to have run into a psychopath in their own lives, psychopaths can cause devastating emotional, financial, and physical damage at the individual level as well. This has made it really important to try to understand how psychopaths come to be. Are they the result of nature or nurture?
I will return to that question in a moment, but first I want to ask an even more basic question—why do psychopaths exist in the first place?
Why do Psychopaths Exist?
For most criminals, the reality is that they suffer from broken childhoods and/or developmental disorders. One of the puzzles about psychopathy is that, unlike other antisocial diagnoses (e.g., antisocial personality disorder or sociopathy), psychopaths often present as very normal individuals in most situations.
For almost 30 years now, some researchers have been arguing that psychopaths aren’t “broken” individuals; rather, they are adaptively pursuing goals using very different social strategies than most people. Their ability to deceive and manipulate others, even when the risks are high, can lead them to rewards such as money or sexual opportunities (Brazil et al., 2024). The risky and promiscuous lifestyle of psychopaths means that most of them are men and they exploit the goodwill of large, mostly cooperative and trusting groups of people around them.
In evolutionary theory, this is known as a frequency-dependent strategy. In a large group of mostly cooperative people, there exist opportunities for a ruthless person to worm their way in and exploit that cooperation. But if too many ruthless people emerge, people stop trusting each other and cooperation goes away—and so does any advantage associated with being psychopathic.
So there may be adaptive biological reasons why psychopaths exist in low frequencies (estimates are 1 in 100-200 people): their ability to exploit others is associated with greater reproductive opportunities, but only if people aren’t aware of them and on guard against them. But how do they come to exist in the first place? Are they shaped by the environment around them or are they born?
Are Psychopaths Born That Way?
Given that psychopathy may have adaptive roots, it stands to reason that like many other aspects of personality, it may also have genetic roots. Indeed, recent studies show that it does seem to have a number of links to heritable traits (De Brito et al., 2021).
Twins studies, that compare identical twins (with the same genes) to fraternal twins (with 50 percent similar genes) repeatedly show that identical twins are more similar on psychopathy scores, suggesting an important effect of genes. Further research has shown that these effects may include genes related to the function of common neurotransmitters, such as dopamine, serotonin, and oxytocin—all of which relate to personality and behavior. So psychopathy does have genetic roots.
Are Psychopaths Made That Way?
Yet as much as evidence suggests that psychopathy may be linked to genes, there is also evidence that suggests it is linked to specific environmental factors. In particular, environmental signals that reinforce the value of exploiting others may play a crucial role in promoting the development of psychopathy.
Psychopathy Essential Reads
Our recent research (Brazil et al., 2024) showed that cues of parental neglect, competitive schools, and dangerous neighbourhoods were all associated with higher levels of psychopathy in adolescents. Given that each of these environmental factors signals how the value of looking out for oneself, their links with psychopathy make sense. Interestingly, lower (or higher) socioeconomic status was not predictive of psychopathy, suggesting that it’s not general hardship or deprivation, but signals of selfishness that trigger the development of psychopathy.
But what’s perhaps most important of all is that these environmental triggers indirectly link psychopathy to valuable adolescent outcomes like dating opportunities and social power. Thus, psychopaths were not only experiencing environments that promoted selfishness, they were experiencing how they could benefit from those environments by expressing their brand of personality traits.
In this way, nature is working with nurture to promote psychopathy. Just like making a chocolate chip cookie requires both the right ingredients and the right oven environment (e.g., time, temperature), psychopathy seems to require the right personality predispositions reinforced by the right environments promoting the right goals (i.e., goals that relate to selfish personality traits).
Where Do We Go From Here?
Changing any personality trait can be a daunting task. We can’t change people’s genes—and it’s very hard to change basic environmental factors like neighbourhoods, schools, and parenting.
The good news is that our most recent research suggests that rather than targeting a broad range of biological or environmental traits, we should perhaps be focusing on intervening against the right intersection of these traits. By focusing our efforts on a particular mixture of biological personality traits and environmental factors, we can narrow our efforts for more effective and targeted interventions that can hopefully reduce psychopathy.
Those will still be costly to do, but they will almost certainly be less costly than the hundreds of millions of dollars in criminal damage that psychopaths do. An ounce of prevention may well be worth a pound of cure!