Affection, particularly from your mother, has a lasting impact on how you develop. (Photo by Jacob Lund on Shutterstock)
In a nutshell
- Parenting matters, even for identical twins. Children who received more maternal affection between the ages of 5 and 10 grew into more open, conscientious, and agreeable young adults than their genetically identical siblings who received less warmth.
- Some traits are shaped by nurture, not just nature. While openness, conscientiousness, and agreeableness were influenced by parenting, traits like extraversion and neuroticism showed no such effect—suggesting those may be more genetically determined.
- Small differences can add up. Though the effects were modest, researchers say even subtle boosts in positive parenting could lead to meaningful population-wide improvements in personality traits that predict education, health, and life success.
EDINBURGH, Scotland — Those warm hugs and bedtime stories from your childhood might be shaping your adult personality more than you realize. New research comparing identical twins has revealed that children who received more maternal affection during their early years grew into young adults who were more open-minded, conscientious, and agreeable—even when compared to their genetically identical siblings who received less warmth.
Published in the American Psychologist journal, this study tackles the age-old nature versus nurture debate in a unique way. By examining differences between identical twins who share the same genetic makeup but experienced different levels of maternal affection, researchers could isolate the specific impact of parenting on personality development in ways that previous studies couldn’t achieve.
The Lasting Impact of a Mother’s Warmth
“Personality traits are strong predictors of important life outcomes, from academic and career success to health and well-being,” says lead study author Jasmin Wertz, Ph.D., from the University of Edinburgh, in a statement. “Our findings suggest that fostering positive parenting environments in early childhood could have a small but significant and lasting impact on the development of these crucial personality traits.”
The researchers emphasize that children who experienced more affectionate parenting during childhood developed into young adults with stronger character traits that could improve outcomes both for themselves and for society as a whole.
Most parents instinctively believe their parenting style matters for their child’s development, but previous research has been mixed on whether these effects last into adulthood or are simply washed away by genetic influences. This study provides some of the strongest evidence yet that parenting in childhood can have lasting effects on personality well into adulthood.
Led by researchers from the University of Edinburgh and Duke University, the study followed 2,232 British twins from birth to age 18, using a clever research design that compared identical twins raised in the same household. This approach effectively controls for genetic influences and shared family environment, two factors that have complicated previous research on parenting effects.
Between the ages of 5 and 10, researchers measured how affectionately mothers spoke about each twin. Later, when the twins reached age 18, a critical transition point from high school to work or further education, researchers assessed their personalities using the widely recognized “Big Five” personality traits: openness, conscientiousness, extraversion, agreeableness, and neuroticism.
The research team found that even between identical twins, the child who received more maternal affection during childhood showed higher levels of openness to experience, conscientiousness, and agreeableness at age 18 compared to their genetically identical sibling. These findings remained consistent even after accounting for potential alternative explanations, such as child behavior problems that might have elicited different parenting responses.
These effects were observed at age 18, when young people are leaving the structured environment of high school and making important life transitions. The personality traits fostered by affectionate parenting may help young adults navigate crucial life challenges at this formative stage.
Which Personality Traits Are Most Affected by Parenting?
The traits influenced by parenting – openness, conscientiousness, and agreeableness – are significant predictors of important life outcomes. Openness relates to curiosity and creativity; conscientiousness to being organized and responsible; and agreeableness to cooperativeness and empathy. Together, these traits can affect educational achievement, career success, and overall well-being.
But not all personality traits were equally affected by differences in parenting. The researchers found no significant differences in extraversion (sociability) or neuroticism (emotional stability) between twins who received different levels of maternal affection. This suggests that these traits may be more strongly determined by genetic factors or influenced by experiences outside the parent-child relationship.
Researchers verified that the results held true regardless of whether personality was rated by research staff or by family members who knew the twins well. They also confirmed that the findings weren’t simply due to extreme cases of abusive parenting, but reflected the impact of varying levels of warmth within the normal range of parenting behaviors.
The researchers also made sure it wasn’t the children’s personalities influencing how their parents treated them. To do this, they looked at whether the twins had behavioral or emotional problems at age 5, issues that might affect how warmly a parent responds. Even after accounting for this, the link between affectionate parenting and personality remained.
While parenting matters for personality development, it’s just one of many factors that shape who we become as adults. Nevertheless, even small effects can have meaningful real-world impacts when considered across entire populations.
“There are many proven ways to support parents, such as policies that improve a family’s financial situation; access to treatment for parents who struggle with mental health problems such as depression; and parenting programs that help parents build stronger relationships with their children,” says Wertz.
The affection you show your children doesn’t just make for a happier childhood; it appears to help build character traits that may serve them well throughout life. Being raised with parental warmth and affection helps children develop into more open-minded, responsible, and agreeable adults who are better equipped to navigate life’s challenges.
Paper Summary
Methodology
This study used a longitudinal twin-differences design to examine how maternal affection during childhood affects personality traits in early adulthood. Researchers followed 2,232 British twins (51.1% female) from birth to age 18 as part of the Environmental Risk (E-Risk) Longitudinal Twin Study. The sample included both identical (monozygotic) and fraternal (dizygotic) twins. Maternal affection was measured when children were 5 and 10 years old using a Five-Minute Speech Sample method, where mothers were asked to describe each child while researchers coded their tone of voice, spontaneity, warmth, and expressions of dissatisfaction. At age 18, researchers measured the twins’ personalities through reports by study interviewers using a 27-item scale capturing the Big Five personality traits. They also collected family member reports to verify results. The twin-differences design allowed researchers to control for shared genetic and environmental factors by comparing differences between twins in the same family.
Results
Twins who received more affectionate parenting during childhood scored higher on openness to experience, conscientiousness, and agreeableness at age 18 compared to their co-twins who received less affection. These associations remained significant even when comparing identical twins, suggesting the effects weren’t simply due to shared genetics or family environment. There were no significant differences in extraversion or neuroticism. The associations were small in magnitude but survived multiple robustness checks, including controlling for reporting source, childhood maltreatment, child effects on parenting, and family support at age 18. The findings suggest that parenting influences personality development beyond early adolescence and that these effects persist into early adulthood.
Limitations
The twin-differences design focuses only on factors that differ between twins, which can magnify measurement error and reduce precision of estimates. There may be unmeasured confounders at the individual-twin level that could account for the observed associations. The study focused only on maternal affection and didn’t measure other aspects of parenting or father’s parenting. The effect sizes, while statistically significant, were relatively small. Additionally, the neuroticism measure had relatively low reliability when measured using interviewers’ reports, though similar findings were observed when using family member reports with higher reliability.
Funding and Disclosures
This research was supported by the US National Institute of Child Health and Human Development (HD077482) and the Jacobs Foundation. Additional funding came from the National Institute for Health and Care Research, the UK Medical Research Council, and the UK ESRC Centre for Society and Mental Health. The authors declared no conflicts of interest.
Publication Information
The study “Parenting in Childhood Predicts Personality in Early Adulthood: A Longitudinal Twin-Differences Study” was published in the American Psychologist journal in 2025. The authors include Jasmin Wertz, Terrie E. Moffitt, Flora Blangis, Antony Ambler, Louise Arseneault, Andrea Danese, Helen L. Fisher, and Avshalom Caspi, representing institutions including the University of Edinburgh, Duke University, King’s College London, University of Oslo, and University of Otago.
