A 16-year study reveals how childhood lying patterns predict adult outcomes

A new longitudinal study published in Development and Psychopathology provides evidence that most children exhibit low or declining levels of lying as they grow up, which generally does not lead to serious problems in adulthood. However, the research also suggests that a small subset of children who lie frequently or show increasing deception over time tends to face a higher risk of developing antisocial personality symptoms and facing criminal convictions later in life.

Deception is a common human behavior that emerges as early as the preschool years. While most people have the cognitive capacity to lie, research shows that the majority of adults do so infrequently. The overall rate of lying tends to decline as people age. However, a small portion of the population lies prolifically, sometimes developing into a problematic habit.

Past research has often viewed lying as a static trait or measured it at a single point in time. The transactional model of lie development offers a different perspective. This framework conceptualizes truthfulness and dishonesty as dynamic behaviors that change over a person’s life. According to this model, a child’s lying habits are shaped by an ongoing interaction between their mental development, their social environment, and their individual personality traits.

Much of the existing research on childhood deception relies on short-term laboratory experiments. These experiments often place children in artificial situations to see if they will lie for a reward or to hide a misdeed. While these studies reveal how children develop the mental skills needed to lie, they do not capture how deception unfolds in real-world settings over many years.

To address this gap, researchers wanted to track patterns, or trajectories, of lie-telling from early childhood into young adulthood. They sought to identify whether distinct groups of children follow different paths of dishonesty as they age.

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“We know that lie-telling abilities emerge in young children due to their developing cognitive abilities (Theory of Mind, executive functioning) and we know from adult literature that most people are predominately honest telling lies only occasionally, while a few are prolific/chronic liars associated with other problem behaviors,” said Victoria Talwar, director of the Daniel and Monica Gold Centre for Early Childhood Development at McGill University’s Faculty of Education.

Theory of mind refers to the ability to understand that other people have different thoughts and beliefs than one’s own, while executive functioning involves mental skills like self-control and working memory.

“But we didn’t know how these trajectories develop,” Talwar said. “We didn’t have the connection between young childhood and adulthood. This data allowed us to look at how individuals lie-telling behavior changed or remained stable across childhood into early adulthood.”

To answer these questions, the scientists analyzed data from the Quebec Longitudinal Study of Kindergarten Children. The sample included 3,017 francophone children living in Quebec, Canada. The group consisted of 47.2 percent girls and 52.8 percent boys who were around six years old when the study began. The participants included a representative group of 2,000 children and a specialized group of 1,017 children who had scored in the top tier for disruptive behaviors in kindergarten.

The researchers tracked the participants for sixteen years. Parents and teachers served as observers, reporting on the children’s lying behaviors at multiple points between the ages of six and nineteen. The adults used a simple three-point scale to rate the frequency of the children’s lies. They chose between “does not apply,” “occasional,” and “frequent.”

Parents also reported on the children’s aggressive behaviors at age six and again at age nineteen. They rated items such as fighting, biting, bullying, and destroying belongings. Teachers provided ratings of the children’s impulsivity at age twelve. This included assessing how often a child acted without thinking or sought attention by shouting.

When the participants reached age twenty-two, trained assistants conducted clinical interviews based on standardized psychiatric guidelines. They assessed the young adults for symptoms of antisocial personality disorder. This mental health condition involves a long-term pattern of manipulating, exploiting, or violating the rights of others, often accompanied by a lack of remorse. The researchers also gathered official juvenile and adult court records for the participants. These records covered criminal convictions between the ages of thirteen and twenty-five.

The scientists then used statistical grouping techniques to identify different pathways of lying behavior based on the parent and teacher reports. Because parents and teachers observe children in very different environments, the researchers analyzed the two sets of reports separately.

The teacher reports revealed three distinct pathways of lying behavior. The vast majority of the sample, comprising 73 percent of the children, fell into a “low lie-telling” group. These children displayed very low rates of lying at age seven, and this behavior declined to almost zero by age fifteen. A second group, making up 22 percent of the sample, followed an “increasing lie-telling” path. Their deception started higher than the first group and slowly climbed to an occasional rate by their mid-teens. A third group based on teacher reports showed a “declining lie-telling” pattern. This group made up 5 percent of the sample, starting with the highest rates of lying but dropping to near zero by age fifteen.

The parent reports also uncovered three unique behavioral pathways. The largest group, making up 58 percent of the children, showed an “occasional lying” pattern. According to parents, these children maintained a stable, moderate rate of lying from age six through age nineteen. Another 30 percent followed a “low lying” trajectory. These children started with low rates of deception that steadily dropped to near zero. The final 12 percent exhibited a “curvilinear lying” path. These children showed moderate lying at age six and experienced a peak in deception around ages eight to ten. After this peak, their rate of lying sharply declined toward zero by late adolescence.

Reflecting on the findings, Talwar noted that the results aligned with the researchers’ expectations. “In many ways this confirmed what we thought but had no evidence to know for sure,” she told PsyPost.

“Most children do not lie too much and tend to lie less as they grow up,” Talwar explained. “We found that the majority showed low or occasional lying and with trajectories that were either stable or declined. Frequent lying is not the norm, only a small minority show increasing or persistently higher levels over time. Thus Lying is typically common in childhood but for most not a sign of major problems for most children.”

The authors found that early problem behaviors predicted which lying path a child would follow. Children who displayed higher levels of aggression at age six were more likely to end up in the higher or increasing lie-telling groups. Similarly, children whom teachers rated as highly impulsive at age twelve were more likely to belong to the more deceptive groups compared to the low lie-telling groups.

“For a small group of children who had aggressiveness in childhood or more impulsivity at adolescence, they were more likely to follow higher-level lying trajectories,” Talwar said. “So problematic lying is often a part of broader pattern of behavioral difficulties, not an isolated issue.”

When examining adult outcomes, the researchers found that long-term patterns of lying were linked to future trouble. Based on teacher reports, the children in the increasing lie-telling group showed more symptoms of antisocial personality disorder in early adulthood than those in the low lie-telling group. They also had more violent and non-violent criminal convictions on their records.

Based on parent reports, the children in the stable, occasional lying group had the highest rates of adult aggression. This group also showed the highest rates of antisocial personality symptoms and criminal convictions. In contrast, children in the low or declining lying groups had the fewest adult criminal records and psychiatric symptoms.

“For those with persistent/higher lying, this predicted later problems: aggression, more symptoms of antisocial personality disorder, and higher rates of criminal behavior (though still generally low overall),” Talwar said. “So persistent, noticeable lying can be an early warning sign of later adjustment problems.”

The findings suggest that persistent lying, when observed alongside other behavioral issues, provides evidence of a trajectory toward maladaptive adult outcomes. “But the key take away for parents is: Most kids lie occasionally and grow out of it but persistent, escalating lying especially alongside behavioral problems can signal increased risk for later antisocial outcomes and warrants early support,” Talwar added.

There are a few potential misinterpretations and limitations to consider. The study relies on a simple three-point scale to measure lying. This broad categorization cannot capture the nuanced motivations behind a lie. It fails to distinguish between a malicious lie told for personal gain and a prosocial lie told to protect a friend’s feelings.

The measurement tool also does not capture the actual frequency of all lies told by the participants. Instead, parents and teachers can only report the lies they actually detect. Adults are notoriously poor at catching children in a lie. Because of this, the study primarily measures socially visible dishonesty rather than the absolute number of lies a child tells.

Talwar pointed out this constraint in the methodology. “These are lies as reported by parents and teachers, not self-reports (which is hard to do at a younger age) or behavioral paradigms,” she said. “Thus, there may be lies that parents or teachers did not catch and report.”

The sample also included a disproportionately large number of children who exhibited disruptive behavior in kindergarten. This overrepresentation might have made it easier to detect links between early behavioral problems and later criminal outcomes. The researchers also did not account for other outside factors. Variables such as a family’s socioeconomic status or untreated internalizing problems, like anxiety, could influence both childhood behavior and adult legal troubles.

Future research should attempt to measure lying using more precise and continuous scales. Scientists might also benefit from examining the specific types of lies children tell across different stages of development. Tracking individuals even further into adulthood could help clarify how childhood deception impacts long-term career success and personal relationships.

“This demonstrates that not all lying is the same,” Talwar said. “In the future, we hope to identify distinct subtypes of chronic lying and their different causes and outcomes. This will help us detect problematic trajectories early and design more effective interventions for early support.”

The study, “The long view: Lie-telling trajectories, ages 6 to 19 years,” was authored by Victoria Talwar, Angela M. Crossman, Kristy Robinson, Marie-Claude Geoffroy, Sylvana Côté, Richard Ernest Tremblay, and Frank Vitaro.