The cross-section of evolutionary psychology, criminology, and developmental psychology paints a powerful picture of how human beings are wired. When looking through this specific lens—frequently articulated by clinical psychologist Dr. Jordan Peterson—childhood is not a blank slate, nor is adulthood infinitely malleable.
The process of how a child transitions from an un-socialized bundle of impulses into a morally integrated adult relies heavily on evolutionary mechanics, structural constraints, and maternal/ paternal balance.
1. Early Development: The Evolution of Morality & Core Values
From an evolutionary psychology perspective, human children are born incredibly dependent compared to other primates. Because of this, early childhood development is hyper-focused on socialization.
Dr. Jordan Peterson frequently references the work of developmental psychologist Jean Piaget to explain how children learn morality. Morality is not just a set of rules memorized from a textbook; it is an evolved, emergent property of human interaction.
- The Sibling/Peer Sandbox: Children learn core value systems by participating in “shared intentionality” and play. Around ages 2 to 4, children transition from parallel play (playing near each other) to cooperative play (playing with each other).
- The Social Contract of Play: To keep a game going, a child must learn to negotiate, share, and manage aggression. If a child behaves too aggressively or unfairly, other children will refuse to play with them.
- The Critical Age 4 Window: Peterson heavily emphasizes a sobering criminological statistic: if a child is not socialized by the age of 4, they face a vastly higher risk of lifelong anti-social behavior and criminality. By age 4, a child must have learned to regulate their impulses and integrate into a peer group. If they miss this window, they are rejected by their peers, fall behind academically, become isolated, and often turn toward counter-cultural or criminal subcultures.
2. Why 27? The “Crystallization” of Personality
The idea that the core of a person becomes largely fixed by their late 20s (around age 27) aligns with modern neuroscience and the Big Five personality trait framework.
Brain Development & Fluid Intelligence
The prefrontal cortex—the seat of executive function, impulse control, and long-term planning—does not fully mature until a person is roughly 25 to 27 years old. Before this point, the brain possesses higher neuroplasticity and fluid intelligence (the ability to think abstractly, reason quickly, and easily adapt to entirely new ideological paradigms).
The Decline of Openness to Experience
As a person passes age 27, their personality traits (Openness, Conscientiousness, Extraversion, Agreeableness, and Neuroticism) stabilize drastically. Statistically, as people age:
- They experience a gradual decrease in Openness to Experience.
- They experience an increase in Conscientiousness and Agreeableness.
By the late 20s, the “Peter Pan” phase of infinite potential must die so that the disciplined adult can be born. Because the brain’s cognitive speed and fluid intelligence begin their very gradual, natural decline around this time, adults become progressively less susceptible to radical new ideologies. They rely instead on crystallized intelligence—accumulated knowledge, structured worldview, and stable habit patterns. The core psychological architecture becomes dense; who you are at 27 is, barring major trauma or intentional, massive effort, generally who you will remain.
3. Pushing Back Against Freud and Forensic Myths
This biological and evolutionary framework stands in sharp contrast to two ideas: historical Freudian psychoanalysis and the Hollywood mythos of forensic behavioral profiling.
┌────────────────────────────────────────────────────────┐
│ THE PSYCHOLOGICAL DIVIDE │
└────────────────────────────────────────────────────────┘
│ │
▼ ▼
┌───────────────────────┐ ┌───────────────────────┐
│ FREUDIAN CLASSIC │ │ EVOLUTIONARY / BIG 5 │
├───────────────────────┤ ├───────────────────────┤
│ • Infinite states │ │ • Strict biological │
│ • Endless malleability│ │ temperament bounds │
│ • Fixations can occur │ │ • Fixed baseline by │
│ at any hidden stage │ │ late 20s │
└───────────────────────┘ └───────────────────────┘
The Critique of Freud’s “Infinite States”
Sigmund Freud viewed the human psyche as an intricate web of infinite fluid states, sexual fixations, and defense mechanisms where a person could theoretically be structurally altered at any point by unearthing the unconscious.
Evolutionary psychology and trait psychologists like Peterson argue against this absolute malleability. Human beings do not have infinite potential states; we are bounded by deeply rooted genetic temperaments. A highly introverted, highly neurotic child cannot be infinitely molded into a fearless, hyper-extroverted adult. Nature sets the boundaries; upbringing simply dictates where within those boundaries the person lands.
The Myth of the “Exact Profile” from Crime Scenes
In criminology, there is a persistent myth—popularized by media and early behavioral profilers—that a criminologist can look at a crime scene and deduce the exact upbringing, exact race, and specific psychological background of a perpetrator.
Modern empirical criminology has heavily walked this back. A crime scene can tell you about a perpetrator’s operational traits (e.g., high impulsivity vs. high organization, which map to low vs. high Conscientiousness), but it cannot give you a biographical blueprint. Profiling is a game of broad statistical probabilities, not psychic deduction.
4. The Critical Role of Two Parents: Mother and Father
Because the developmental window closes so early and firmly, the stabilizing presence of both a mother and a father is biologically and socially defensive against criminal trajectories. Dr. Peterson frequently highlights the distinct, evolutionary roles that mothers and fathers play in preventing a child from becoming a pathological or criminal adult.
- The Maternal Shield (Encouragement & Security): Mothers historically provide the primary matrix of security, emotional regulation, and immediate protection. This unconditional baseline of support gives the child the psychological safety required to trust the world.
- The Paternal Boundary (Encouragement to Edge of Danger): Fathers, from an evolutionary standpoint, tend to introduce the child to the external, unpredictable world. Peterson points to rough-and-tumble play (typically driven by fathers) as a crucial developmental tool. When a father wrestles with a 3-year-old, the child learns the exact boundaries of physical aggression. They learn what hurts, how to tolerate minor distress without crying, and when to stop. This directly inoculates the child against predatory or anti-social aggression.
The Criminological Cost of Fatherlessness
In criminological literature, the single greatest statistical predictor of youth crime, incarceration, and systemic failure is fatherlessness. Without both parental dynamics balancing each other out—one pulling back toward safety, the other pushing outward toward calculated risk and boundary-testing—a child is far more likely to fail the “Age 4 Socialization Test,” setting off a domino effect that hardens permanently by the time they hit 27.
You can explore Dr. Peterson’s detailed breakdown of how aggressive tendencies in toddlers are socialized (or fail to be) by looking into this Jordan Peterson Criminology Interview. This talk provides further context on the statistical links between childhood development, parental presence, and adult criminality.