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  • Family instability in childhood appears to lead to an increase in deception, coldness, impulsivity, and aggression, and to a decrease in kindness, trust, generosity, and honesty. Tweet This
  • The effect of instability in childhood on adult criminal behavior is equivalent to the effect of family socioeconomic status on SAT scores. Tweet This

Consider this: Children in poor families tend to have better outcomes than children raised in foster homes, as I noted in a piece for Psychology Today. 

This is striking because when it comes to important outcomes like graduation rates, drug use, future earnings, and criminal behavior, much of our focus is on economic factors.

But in fact, family instability appears to be a stronger predictor than family socioeconomic status for a child’s life trajectory. Elites endlessly focus on the influence of wealth on standardized test scores. Seldom do they discuss how instability in childhood gives rise to harmful behaviors in adulthood. For example, the effect of instability in childhood on adult criminal behavior is equivalent to the effect of family socioeconomic status on SAT scores.

It is possible that such detrimental behaviors are the result of changes in two important personality constellations: The Dark Triad and the Light Triad. The Dark Triad encompasses three traits:

  1. Narcissism (grandiosity, self-importance, entitlement)
  2. Psychopathy (callousness, cynicism, impulsivity)
  3. Machiavellianism (strategically exploitative, duplicitous, manipulative)

In a 2016 study published in Evolutionary Psychology titled, “Resources, Harshness, and Unpredictability: The Socioeconomic Conditions Associated with the Dark Triad Traits,” researchers measured Dark Triad traits in people. Participants rated how much they agreed with statements such as:

  • “Many group activities tend to be dull without me” and “People see me as a natural leader” (Narcissism)
  • “People who mess with me always regret it” and “I like to pick on losers” (Psychopathy)
  • “It’s wise to keep track of information that you can use against people later” and “Avoid direct conflict with others because they may be useful in the future” (Machiavellianism)

Participants also responded to various statements about their childhood including:

  • “My parents had a difficult divorce or separation during this time” and “People often moved in and out of my house in a pretty random basis” (childhood instability)
  • “I grew up in a relatively wealthy neighborhood” and “My family usually had enough money for things when I was growing up” (childhood socioeconomic status)

Researchers found that instability in childhood significantly predicted all three dimensions of the Dark Triad in adulthood. The strongest link was with psychopathy (r = .23). Across the entire Dark Triad scale, the correlation was = .20. This is not especially large, but it is still noteworthy. The effect is roughly equivalent to the link between school grades and future earnings.
The effect of childhood unpredictability was especially large for men, relative to women. That is, boys raised in unstable homes were particularly likely to have high Dark Triad scores in adulthood compared to girls raised in unstable homes.  

Importantly, childhood socioeconomic status had no association with Dark Triad traits in adulthood. Being poor doesn’t have the same effect as living in chaos. The researchers concluded, 

All people may have the potential to be high or low on the Dark Triad traits…exposure to specific conditions is the precipitating factor, which determines people trait activation and position on the Dark Triad continuum. Experiences (or at the very least, recollection of) of childhood unpredictability may be some of the prerequisite conditions to active the dormant selfishness, competitiveness, and antisociality found in the Dark Triad traits.

Still, many might wonder about the role of genetics when it comes to these traits. In his book Machiavellianism: The Psychology of Manipulation, the psychology professor Tamás Bereczkei writes that, “Although genetic factors may have a certain role in the development of the Machiavellian lifestyle and thinking, Machiavellianism is primarily a result of environmental effects.” He shares research from twin studies indicating that genes account for only 31% of the differences between people for the personality trait of Machiavellianism. In other words, the environment is more important than genes for this Dark Triad trait. 

Family instability appears to be a stronger predictor than family socioeconomic status for a child’s life trajectory.

Additionally, others have suggested that environmental factors can affect the behavioral expression of psychopathy.
Robert Hare, the world’s foremost expert on psychopathy, argued that 

social factors and parenting practices help to shape the behavioral expression of psychopathy, but have less effect on the inability to feel empathy or develop a conscience. No amount of social conditioning by itself will generate a capacity for caring. 

Hare is saying that the psychology of psychopaths can’t be changed. Nevertheless, the behavioral expression of psychopathy can be shaped and contained by parental and environmental factors. For fans of the television series Dexter, this was the reasoning behind “The Code of Harry.” Dexter’s adoptive father recognized that Dexter would always have homicidal urges, so he directed his son's impulse away from innocent people.

In a real life case of psychopathy, a few years ago, a neuroscientist named James Fallon discovered that he himself is a psychopath. Once a self-proclaimed genetic determinist, he changed his mind when he considered how his warm upbringing constrained his malevolent impulses. “I was loved, and that protected me,’” he explained.

Fallon believes that had he been raised in a different environment (i.e., not in an intact middle- class family), his life would look very different today.

It is important to note that the Dark Triad is not a diagnostic tool for personality disorders. It measures subclinical psychopathy and narcissism. Though if someone scores at the uppermost end of those sub-scales, they might qualify for an official diagnosis.
Now onto the Light Triad. This is a constellation of three prosocial traits:

  1. Humanism (appreciation of the successes and creations of others)
  2. Kantianism (tendency toward behaving with integrity and honesty rather than deceit and charm)
  3. Faith in humanity (believing that people are generally good and worthy of trust)

To be clear, both the Light and Dark Triad concepts exist on a spectrum. There is a bit of both in all of us. But a person who scores particularly high on one or the other would be someone to either trust or avoid.  

In a 2019 study,” a team of researchers led by Scott Barry Kaufman asked people how much they agreed with statements like:

  • “I tend to applaud the successes of other people” and “I enjoy listening to people from all walks of life” (Humanism)
  • “I prefer honesty over charm” and “When I talk to people, I am rarely thinking about what I want from them” (Kantianism)
  • “I tend to see the best in people” and “I tend to trust that other people will deal fairly with me” (Faith in humanity)

Participants also responded to statements about their childhood family income and childhood unpredictability. The researchers found that instability in childhood predicted lower Light Triad traits in adulthood (r = -.21). 

Crucially, childhood socioeconomic status had no relationship with Light Triad traits in adulthood. This mirrors the finding that childhood socioeconomic status did not predict Dark Triad traits in adulthood. The finding is consistent with the notion that growing up poor doesn’t have the same effect as growing up in chaos. 

In short, family instability in childhood appears to lead to an increase in deception, coldness, impulsivity, and aggression. Conversely, instability in childhood is linked to a decrease in kindness, trust, generosity, and honesty. If we want less psychopathic behavior and more humanistic behavior, then promoting stable and secure families for children would be a good place to start. 

Rob Henderson is a doctoral candidate at the University of Cambridge, where he studies as a Gates Cambridge Scholar. He obtained a B.S. in Psychology from Yale University, and is a veteran of the U.S. Air Force.

Editor's Note: This essay appeared first in the author's personal newsletter. It has been lightly edited.