What shapes a person’s character? For most of human history, that question was answered in relatively simple terms: biology, upbringing, and personal choice. Yet an ambitious new study published in one of science’s most prestigious journals has added a striking variable to that equation – one that most people would not immediately think to include. The society you live in, including how corrupt it is, how unequal, how violent, and how impoverished, may play a measurable role in determining whether you develop what psychologists call “dark” personality traits: selfishness, manipulation, a callous disregard for other people.
This finding doesn’t just raise philosophical questions about free will and individual responsibility. It has concrete implications for how we understand rising social dysfunction, political distrust, and the kind of interpersonal predation that shows up in workplaces, relationships, and communities everywhere. If the conditions of a society can tilt its citizens toward narcissism or psychopathy over time, then the way we govern, distribute resources, and enforce laws is also, in some sense, a matter of collective psychological health.
The research behind this conclusion is large-scale, unusually rigorous for its kind, and difficult to dismiss. It draws on data from nearly 2 million people across 183 countries and all 50 U.S. states – a dataset of a breadth rarely seen in personality psychology. And its findings arrive at a moment when questions about societal toxicity, institutional trust, and the health of democracies are more pressing than ever.
The Study: Scope, Design, and What It Measured
The research examined whether aversive societal conditions – assessed specifically through corruption, inequality, poverty, and violence – could explain individuals’ levels of aversive personality, measured through what the researchers call the Dark Factor of Personality.
The study used data from 1.8 million people in 183 countries and 144,000 people in the United States. It was conducted by five researchers: Ingo Zettler, Lau Lilleholt, and Martina Bader from the University of Copenhagen, as well as Benjamin E. Hilbig from the University of Kaiserslautern-Landau and Morten Moshagen from Ulm University. It was published in the Proceedings of the National Academy of Sciences, volume 122, issue 20, in May 2025.
To quantify societal adversity at the global level, the team used World Bank data on corruption (control of corruption), inequality (Gini index), poverty (headcount ratio at $6.85/day), and violence (homicides per 100,000 people). For U.S. states, they used Census Bureau data on inequality and poverty, FBI homicide rates, and Justice Department corruption convictions. These metrics allowed consistent comparisons across global and state-level contexts to assess long-term societal conditions.
Critically, the researchers combined the personality questionnaire data with objective data on countries’ and U.S. states’ social conditions, assessed approximately 20 years before the personality measurement was taken. That time lag is important. It means the study was not simply looking at correlations at a single point in time. It was testing whether conditions that existed roughly two decades earlier predicted higher levels of dark personality traits in populations today – a design that strengthens the case for a causal relationship, though it does not fully prove one.
What Is the “Dark Factor of Personality”?
Before going further, it helps to understand what the researchers were actually measuring. The Dark Factor of Personality, or D, is not simply a synonym for the more familiar “Dark Triad” of narcissism, Machiavellianism, and psychopathy. It is the common underlying core from which those and other aversive traits arise.
Many negatively connoted personality traits, often termed “dark traits,” have been introduced to account for ethically, morally, and socially questionable behavior. Researchers identified a unifying framework for understanding dark personality in terms of a general dispositional tendency from which dark traits arise as specific manifestations. That common core is called the Dark Factor of Personality (D). D captures individual differences in the tendency to maximize one’s individual utility – disregarding, accepting, or malevolently provoking disadvantage for others – accompanied by beliefs that serve as justifications.
The Dark Factor of Personality represents the “aversive essence of personality,” from which all other aversive traits, such as egoism, spitefulness, greed, moral disengagement, sadism, psychopathy, and Machiavellianism, arise.
In practical terms, a person who scores high on D isn’t necessarily a violent criminal. They may simply be more likely to cheat, exploit, manipulate, or act with contempt for others’ well-being – and to rationalize doing so. The dark triad, first described by psychologists Delroy Paulhus and Kevin Williams in 2002, describes three notably offensive but non-pathological personality types: Machiavellianism, sub-clinical narcissism, and sub-clinical psychopathy. Each is considered dark because each contains malevolent qualities.
The Core Finding: Society Shapes Darkness
By combining personality questionnaire results with objective data on countries’ and U.S. states’ social conditions assessed approximately 20 years before, the researchers found a clear – albeit moderate – relation. “The more adverse conditions in a society, the higher the level of the Dark Factor of Personality among its citizens. This applies both globally and within the United States,” says Ingo Zettler, professor at SODAS and the Department of Psychology at the University of Copenhagen.
The study found that countries such as Indonesia and Mexico, or U.S. states such as Louisiana and Nevada, have higher “Dark Factor” levels than countries such as Denmark and New Zealand, or states such as Utah and Vermont, which have better societal conditions in terms of lower corruption, inequality, poverty, and violence.
The researchers were careful to note the association’s magnitude. Although the observed link between environment and personality was moderate, the authors emphasize its real-world consequences. In personality research, even moderate relationships at the population level can translate into substantial differences in societal functioning when aggregated across millions of people. As Zettler put it, “Aversive personality traits are associated with behaviors such as aggression, cheating, and exploitation – and thus with high social costs. Therefore, even small variations can lead to large differences in how societies function.”
The Mechanism: How Adversity Breeds Dark Traits
How does a corrupt or unequal society actually push individuals toward dark personality traits? The researchers point to a logical chain rooted in social learning theory. As Zettler explained, “In societies where rules are broken without consequences and where the conditions for many citizens are bad, individuals perceive and learn that one should actually think of oneself first.”
This molding process can occur through a combination of social learning, situational pressures, and reinforcement loops that strengthen certain patterns of behavior. The dark factor would therefore emerge in societies where children learn that to survive, they have to avoid being exploited. Children also learn by watching what happens to people who exhibit D-like behaviors, and whether these are condoned or punished.
In other words, if the social environment consistently signals that self-interest pays and that institutions cannot be trusted, individuals adapt. They become more likely to cheat before they get cheated. They become more suspicious, more guarded, and over time, more willing to harm others for personal gain – because experience has taught them that a different approach doesn’t work.
The study’s design could take advantage of aversive social condition indices from prior decades, allowing for a lagged-prediction effect. The authors hypothesized that high levels of adverse conditions would promote, over time, adoption by individuals of more “competitive, distrusting, and normless beliefs,” and the findings supported this hypothesis, showing that the four conditions were associated in a time-lagged manner with higher scores on the D measure.
What the Data Reveals About the U.S.
The within-U.S. analysis is particularly striking, because it controls for many of the cultural variables that might complicate international comparisons. All 50 U.S. states share a common language, legal framework, and broad cultural context – yet the variation in dark personality levels across states maps closely onto variation in corruption, inequality, poverty, and violence.
States with persistently higher levels of those adversity indicators show higher population-level D scores. States with lower adversity scores show lower D scores. The pattern holds even after accounting for the 20-year time lag, suggesting that the relationship is not simply a snapshot of current conditions but reflects the cumulative shaping effect of a society’s conditions over years.
This has direct implications for policy debates in the U.S. Persistent inequality, underfunded public institutions, and high rates of community violence are not merely economic or public safety problems. According to this research, they may also be shaping the psychological character of the populations who live within them – slowly, across generations.
Read More: Signs of a Toxic Personality
The Nature vs. Nurture Question, Revisited
One of the enduring debates in personality psychology is how much of who we are is innate versus environmentally shaped. Trait-based theories have historically emphasized genetics and stable biological dispositions. Trait approaches to personality often regard genetics as the foundation on which all dispositions rest. If a person is lucky, their constitution gives them a set of positive features, but if not, they may seem condemned to a life in which personality weaknesses lead to poor outcomes. There is something about trait theories of personality that tends to give more weight to nature than nurture in explaining how people develop over time.
The Copenhagen study pushes back against that framing directly. As Zettler concluded, “Our findings substantiate that personality is not just something we are born with, but also shaped by the society we grew up and live in. This means that reforms that reduce corruption and inequality not only create better living conditions just now – they may also contribute to mitigating aversive personality levels among the citizens in the future.”
This does not mean genetics are irrelevant. Prior research on the heritability of personality traits remains robust, and the researchers acknowledged that genetic factors play a role. What this study adds is evidence that the social environment can independently shift the distribution of dark traits across a population – a finding with profound implications for how we think about social reform.
It also aligns with the growing consensus in developmental psychology that personality, even in adulthood, is more malleable than older models suggested. The Dark Factor of Personality is conceptualized as the basic disposition out of which “dark” traits arise as specific manifestations, and a four-year longitudinal study has critically tested this conceptualization across nine dark traits. Those traits showed high rank-order stability – meaning individuals who scored high tended to stay high – but the new population-level data suggests that the starting point for that stability is itself shaped by the social world.
Limitations and Cautions
Any responsible reading of this research requires confronting its limitations. The study is observational and cross-sectional at its core, even if the time-lag design adds some directional weight. It cannot prove that adverse societal conditions cause dark personality traits – only that the two are associated in a consistent, time-ordered pattern across a very large and diverse sample.
There is also the question of reverse causation. Could it be that populations with higher levels of dark personality traits are more likely to create corrupt, unequal, and violent societies – rather than the other way around? The researchers acknowledge this possibility. The 20-year lag helps address it somewhat, but does not eliminate it. It is plausible that both processes operate simultaneously, with adverse conditions and dark personalities reinforcing each other in a feedback loop.
The personality data itself was collected via an online questionnaire hosted on the researchers’ own website, meaning the sample – while vast – was self-selected rather than randomly drawn from each country or state. People who complete online personality tests may not be fully representative of their broader populations.
Finally, the study measures the Dark Factor at the population level, not as a clinical diagnosis. High D scores are not the same as personality disorder diagnoses. The findings tell us about average tendencies within populations, not about any individual person. A person raised in a high-adversity environment may develop strong prosocial traits. A person raised in a low-adversity environment may still develop harmful ones. The relationship is probabilistic, not deterministic.
Social Costs and the Case for Structural Reform
Despite those caveats, the study’s findings carry real-world weight – particularly for policymakers and those who shape social institutions. The extreme manifestations of dark personality traits take a high toll on society both when considered separately and together, accounting for financial, socioecological, and psychological costs. For example, the engagement of psychopathic individuals in criminal activity has been associated with massive societal monetary losses.
Research published in Humanities and Social Sciences Communications in 2025 has also linked dark personality traits – particularly psychopathy and narcissism – to heightened engagement in harmful online behavior, including online political aggression and coercion, suggesting the societal costs extend well beyond direct interpersonal harm.
Dark triad traits are positively related to antisocial, exploitative, and aggressive behaviors, including both offline and online aggression. Empirical evidence further supports these links: individuals high in Dark Triad traits are more prone to engage in criminal or norm-violating acts and exhibit reduced altruistic tendencies and environmental concern.
The Copenhagen study’s policy implication is direct. If reducing corruption, narrowing inequality, alleviating poverty, and decreasing community violence can reduce the prevalence of dark personality traits in a population over the following two decades, then social reform is not just an economic or humanitarian goal. It is also a psychological one. The kind of society a government builds may, over time, shape the kind of citizens it produces – including how willing those citizens are to exploit, manipulate, and harm one another.
That reframing matters. Debates about reducing inequality are often cast in purely economic terms. This research adds a psychological dimension that is harder to dismiss: structural adversity does not just make life harder for the people living within it. It may, over a generation, make those people harder on each other.
You can explore more about the psychological characteristics associated with difficult relationship dynamics with The Hearty Soul’s coverage of narcissism.
Read More: 20 Signs of a Toxic Person You Shouldn’t Ignore
Key Takeaways
The research coming out of the University of Copenhagen represents one of the largest and most methodologically ambitious attempts to link societal conditions to population-level personality variation. Several conclusions emerge clearly.
First, the association between adverse societal conditions – corruption, inequality, poverty, and violence – and higher levels of dark personality traits is real, consistent, and statistically robust across 183 countries and all 50 U.S. states. The effect is moderate in size but meaningful at scale.
Second, the 20-year time lag built into the study design strengthens the case that this relationship is not merely a snapshot but reflects a genuine developmental influence. Conditions that existed roughly a generation ago appear to predict the psychological profile of populations today.
Third, this does not mean that individuals are simply products of their environment with no agency. The relationship is probabilistic. Many individuals who grow up in high-adversity conditions develop strong prosocial values. But at the population level, the pattern is clear and consistent enough to demand attention.
Fourth, the findings carry direct implications for policymakers. Structural reforms that reduce corruption, narrow inequality, lift people out of poverty, and reduce community violence may do more than improve material living standards. They may, over time, shift the psychological culture of a society – producing populations that are less exploitative, less manipulative, and more oriented toward cooperation and trust.
Finally, the research reframes a question that has often been treated as purely individual. Whether someone becomes narcissistic, exploitative, or callous is not only a matter of their genes or their specific upbringing. It is also, to a measurable degree, a matter of the society they were shaped by. That insight does not reduce individual responsibility. It adds to it – because it means that the conditions we allow to persist in our societies are conditions we are, collectively, choosing to impose on the next generation’s character.
AI Disclaimer: This article was created with the assistance of AI tools and reviewed by a human editor.
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