Why do people become rebellious in adolescence, especially in the family? The neuroscientific explanation

Anyone who lives with a teenager at home, sooner or later, always asks himself the same question: why is he so impulsive, so rebellious, so attracted to everything that is risky or forbidden? The answer does not have to do with character or the education received, but with a precise biological phenomenon, which developmental neuroscience knows well: the rational part of the brain, in this phase of life, is not yet fully mature.

A brain that matures at different speeds: what happens in adolescence

The human brain does not develop uniformly, but goes through different stages in which the various areas mature at different rates and ages. Let’s start from the beginning.

During childhood, the brain areas that manage the simplest functions, for example vision, movement, touch, hearing, already reach sufficient maturity. In the same period, within the first decade of life, it also ventral striatum — the headquarters of nucleus accumbensthe heart of reward circuit — stops growing and reaches its definitive volume. Amygdala and hippocampushowever, follow a longer path: they continue to grow in volume well beyond childhood, up to early adulthood. This is confirmed by a recent review in Communications Biology, which summarized the data from over 120,000 MRIs collected on more than 100,000 people from birth to old age — the project behind the famous “brain charts” published on Nature in 2022.

It is with the arrival of puberty that the history of the ventral striatum takes a different turn. Its volume, as mentioned, no longer changes. However, its reactivity changes: it becomes much more sensitive to rewarding stimuli. A study published in 2026 in Neuropsychopharmacology, conducted on over 200 functional MRIs collected longitudinally on children followed for two years, showed that the connectivity Between prefrontal cortex And striated is associated with sensitivity to reward differently depending on the stage of pubertal development achieved — with effects that also differ between males and females. In other words, the link between the hormonal changes of puberty and the sensitivity of the reward circuit exists, but it is more complex and sex-specific than suggested by the very simplified idea of ​​a single hormonal switch that “turns on” the dopamine.

On the other side there is the prefrontal cortexthe most rational area, which deals with planning, impulse control, evaluation of consequences of a choice. Its development is much slower and linear, and is completed only around the age of 20-25.

Why this marked difference in times? It’s partly a matter of evolutionary hierarchy: subcortical structures linked to emotions are phylogenetically older and respond directly to the hormonal signal of puberty. The prefrontal cortex, on the other hand, is the evolutionarily most recent and most complex area of ​​the entire brain: it manages functions that require the integration of many different pieces of information, and its maturation largely depends on experience — the more complex a function is, the longer the circuit that supports it takes to refine itself. The result, in this specific phase of life, is a temporary imbalance that lasts for years: a hyper-reactive and very powerful emotional system, already almost fully operational, and a control system still under construction. It’s not that a teenager is unable to control himself due to weakness of character: it’s that the system that should allow him to do so is not yet biologically ready.

How the relationship with parents changes

The need for autonomy that characterizes adolescence is not a sign that something is wrong: it is the brain’s way of starting to ask itself “who am I without my family?”. To respond, you need to distance yourself — and often this involves disagreeing with your parents’ rules.

It is worth overturning the most widespread perspective on this point: a child who argues, who opposes, who tests the authority of his parents is building an autonomous identity. The alarm bell, if anything, could be the always compliant child, who risks reaching adulthood without ever having really trained his ability to handle a conflict or assert a personal point of view.

A meta-analysis that brought together data from over 50 studies on conflict between parents and adolescents confirms that it is a normative developmental phenomenon – most arguments concern everyday issues, not conflicts of deep values ​​- whose intensity, however, tends to increase in early adolescence, reach a peak around the age of 16, and then progressively decline. The same body of research underlines that the critical point is not the presence of conflict itself, necessary for the construction of new family balances, but its possible transformation into prolonged hostility, which is instead associated with worse psychological adaptation.

The family as a system: parents and children influence each other

For a long time the relationship between parents and children has been described as a one-way process: the parent educates, the child receives. The most recent research instead shows a reciprocal relationship, in which the behavior of each continuously influences that of the other. A 2023 study in Scientific Reports, which followed 159 families with teenage children for 100 days, confirms that this bidirectional influence really exists, but varies from family to family: depending on the educational dimension considered, between 11% and 55% of families show it day by day, while elsewhere one direction or the other prevails.

This reciprocity involves the entire family system, not just the direct parent-child relationship: 2023 research in Frontiers in Psychology shows how couple conflict between parents can increase the risk of behavioral problems in adolescents also indirectly, through dynamics with siblings. In short, the family is a set of interconnected relationships in which a change in one part is reflected, sooner or later, on all the others.

Because the approval of friends matters more than that of parents

During adolescence, the brain gives top priority to social signals from the peer group. It is not just a psychological question: a 2025 study that analyzed brain structure and function together with reactivity to social exclusion (measured with the classic experimental paradigm of “Cyberball”, a virtual game in which the subject is excluded from other players) confirms that this experience involves the same areas – such as the cingulate cortex and the insula – implicated in the processing of physical pain. At the same time, the approval of peers activates the neural networks involved in primary rewards: this is why, in the presence of the group, the search for risk and novelty tends to amplify further.

Risk and rebellion have an evolutionary advantage

A review published in 2025 in the Annals of the New York Academy of Sciences, authored by BJ Casey, starts from a direct observation: the adolescent brain has often been described as a defective car, equipped only with an accelerator and without brakes or a steering wheel. Read from an evolutionary perspective, many of the typical characteristics of adolescence – the greater sensitivity to emotions, the drive to explore new environments, the attention to social signals – are functional to a specific task: learning to obtain resources and move in the world independently, precisely at the moment in which one moves away from the caregiver.

In this reading, the conflict with parental authority, the attraction towards the peer group and the greater propensity to risk are not defects of a still incomplete system, but traits selected because they have allowed, in the history of our species, to leave the nest, explore new environments and form bonds outside the family group of origin. In short, adolescence can be read as the last great window of plasticity that the brain has available to specialize in view of the adult world it will have to face.