Our primary aversion is not to inequality itself, but to the perception of unfairness—specifically, when someone is rewarded without contributing their fair share. This "freeloader alert" is a deeply ingrained evolutionary mechanism for enforcing cooperation in social groups.
Counterintuitively, the heritability of traits like cognition and personality increases from childhood into adulthood. This occurs because individuals increasingly select and shape their own environments based on their genetic predispositions, a process that amplifies the influence of their genes over time.
Genes linked to addiction, impulsivity, and aggression are most active during fetal development, affecting the brain's fundamental balance of inhibition and excitation. This reframes addiction and conduct disorders as neurodevelopmental conditions akin to ADHD, rather than purely as choices or moral failings.
The traits that manifest as adolescent delinquency—such as high risk tolerance and sensation-seeking—can be highly adaptive in other contexts. Studies of successful young entrepreneurs often find a history of minor delinquency, suggesting these underlying personality traits are well-suited for the risks of starting a business.
Direct-to-consumer genetics companies often market DNA results as revealing "who you really are." This fosters genetic essentialism—the false idea that genes are destiny. This mindset is risky, as it can lead people to internalize genetic predispositions as unchangeable flaws or "bad seeds."
Early pubertal timing in girls—more so than the rate of development—is a strong predictor of future health risks, including mental health issues, earlier menopause, and a shorter lifespan. This suggests a deep biological trade-off between reproductive maturity and longevity, observed across species.
People often frame a person's situation as a "choice" to justify punishment or unsympathetic treatment. This linguistic move shifts blame onto the individual, providing a moral license to enact punishment. This pattern is prevalent in contexts ranging from airline policies to broader political discourse.
While observing suffering typically activates empathy circuits, the brain's reward system activates if the person is perceived as a wrongdoer. This biological mechanism creates a powerful, lust-like desire to see punishment enacted, which psychologist Kathryn Paige Harden refers to as a "cruelty currency."
The onset of antisocial behavior before age 10 is one of the biggest predictors of a lifelong pattern of offending. Cold, callous aggression towards others or animals at this young age, often with a heavy genetic component, has a poor prognosis and currently has vanishingly few effective treatments.
Research shows that the same genetic predispositions for physical aggression (e.g., fighting) in boys can manifest as relational aggression (e.g., social exclusion, reputation damage) in girls. This highlights a common biological root for sex-differentiated expressions of aggression, which can be equally damaging.
In economic games, groups where members can punish others for not contributing to the collective good quickly establish strong cooperative norms and thrive. In contrast, groups without a punishment mechanism collapse as individuals act in their own self-interest, causing members to ultimately migrate to the more successful, punishing society.
In cases of extreme violence, we seldom investigate underlying biological factors unless there's an obvious "smoking gun" like a brain tumor. The discovery of a rare MAOA gene mutation causing extreme aggression in a Dutch family raises the question of how often people are labeled as "evil" without any search for an organic cause.
While boys and girls show similar sensation-seeking during adolescence, there's a decade-long gap in the maturation of impulse control. The average male's inhibitory control only reaches the level of a typical 15-year-old girl around age 24, highlighting a significant developmental difference between the sexes.