Children who receive more warmth and affection from their mothers grow into more open, conscientious, and agreeable young adults, according to a new study published in American Psychologist. The findings, drawn from a long-running twin study in the United Kingdom, suggest that parenting may have lasting effects on certain personality traits—even after accounting for genetic and environmental influences.
Researchers have long been interested in how early life experiences shape who we become. Personality traits like openness, conscientiousness, extraversion, agreeableness, and neuroticism are known to predict many outcomes in adulthood, including career success, relationships, and mental and physical health. These traits, sometimes referred to as socioemotional skills, are also viewed as potentially malleable—especially compared to traits like intelligence—raising hopes that interventions in childhood could support healthier development.
One key question is whether parenting plays a meaningful role in shaping personality, and if so, how long that influence lasts. Previous studies have shown that positive parenting is linked to personality traits during childhood and adolescence. But few have followed children into adulthood, and many studies cannot rule out the possibility that genetics or shared family environments drive these associations.
To address this gap, a team of researchers led by Jasmin Wertz at the University of Edinburgh used a powerful study design involving monozygotic (identical) twins. Because these twins share 100% of their genes and the same family environment, any differences between them can more confidently be attributed to differences in experience. In this case, the researchers focused on maternal affection—measured during early childhood—and how it related to personality traits at age 18.
“We knew from previous research that the way parents treat their children – such as how affectionate and supportive they are – is linked with how children’s personalities develop,” explained Wertz, an assistant professor of psychology. “However, it is difficult to know whether these links are the result of parenting itself, or because parents pass on genes to their children. By studying twins who share all of their genes and grow up in the same home, we were able to study the effects of parenting separately from the effects of genes, to see if parenting has an effect on young people’s personalities.”
The data came from the Environmental Risk (E-Risk) Longitudinal Twin Study, which followed a nationally representative cohort of 1,116 British families with same-sex twins born in 1994–1995. Maternal affection was measured at ages 5 and 10 using the Five-Minute Speech Sample method, where mothers were asked to talk freely about each of their children. Researchers rated the tone and content of these recordings for warmth and dissatisfaction, providing a measure of affectionate parenting. At age 18, twins’ personalities were assessed using both interviewer ratings and reports from family members.
The analysis showed that, across the full sample, higher levels of maternal affection predicted greater openness, conscientiousness, and agreeableness, as well as slightly higher extraversion and lower neuroticism. These findings held even when adjusting for variables like sex and clustering within families.
But the study’s most revealing results came from comparisons within twin pairs. Even among identical twins raised in the same household, the twin who received more maternal affection was more likely to be open, conscientious, and agreeable as a young adult. These associations remained even after controlling for early emotional and behavioral problems, experiences of maltreatment, and the level of family support at age 18. In contrast, the links between maternal affection and the traits of extraversion and neuroticism disappeared in the twin comparison models, suggesting those associations may be explained by shared genes or environment rather than parenting alone.
“We were not surprised by finding positive effects of parenting for young people’s open-mindedness, conscientiousness and agreeableness, as we had expected that affectionate parenting would be linked with twins’ differences in these traits,” Wertz told PsyPost. “However, it was surprising that parenting was not linked with the other personality traits, particularly with twins being less neurotic.”
These findings provide rare and rigorous evidence that the emotional tone of parenting—not just the presence of abuse or neglect—can shape personality well into young adulthood. Importantly, the effects held even when personality was assessed by people outside the family, reducing the chance that mothers’ views on their parenting were simply mirrored in how they rated their children.
“Our findings imply that when parents are supported in being more affectionate in their relationships with their children, it can have an impact on how children’s personalities develop,” Wertz explained. “There are many proven ways to support parents, such as parenting programmes that help parents build stronger relationships with their children, but also policies that improve a family’s financial situation or make it easier for parents to access treatment if they struggle with mental health problems such as depression.
“The personality traits we found effects for – being open-minded, conscientious and considerate – are not only important for young people themselves, but they also matter for how they contribute to society. Supporting parents can therefore have a wide-reaching positive impact for society.”
The study challenges a view held by some behavioral geneticists that differences in personality are largely shaped by random or unpredictable factors in the environment. The fact that identical twins raised in the same household can differ in personality based on differences in parenting suggests that specific, modifiable experiences do matter.
But the authors caution against overgeneralizing the findings. The measure of parenting focused only on maternal affection, leaving open the question of how other parenting styles or paternal behaviors might influence development. The effects were also statistically modest.
“All findings were quite small, so the findings should not be misinterpreted to mean that affectionate parenting is all that matters for personality,” Wertz noted. “Also, the young people were 18 years old, which is still quite young. The young people in the study are currently being followed up, which will make it possible to test whether the effects of parenting last even longer. We are also working on repeating our study in a German cohort, to test if effects are generalizable across other settings and contexts.”
The study, “Parenting in Childhood Predicts Personality in Early Adulthood: A Longitudinal Twin-Differences Study,” was authored by Jasmin Wertz, Terrie E. Moffitt, Flora Blangis, Antony Ambler, Louise Arseneault, Andrea Danese, Helen L. Fisher, and Avshalom Caspi.
