Summary: Methylation of the oxytocin gene (OXT) was linked to greater maternal personal distress and to reduced gray matter volume in the right inferior temporal gyrus, findings that connect epigenetic variation with caregiving behavior and brain structure.
Source: University of Fukui
Empathy — the ability to sense and understand another person’s feelings — is essential to caregiving, cooperation, and positive parent–child relationships.
Researchers generally distinguish two forms of empathy. Cognitive empathy refers to understanding another person’s perspective and emotions at an intellectual level, often described as “putting yourself in someone else’s shoes.” Affective empathy, by contrast, is an emotional response that mirrors another person’s feelings, an instinctive emotional resonance triggered by facial expressions or other cues.
Both cognitive and affective empathy strongly influence how parents interact with their children and, in turn, shape children’s psychological development. Clarifying biological factors that shape empathy can therefore help explain differences in parental behavior and child outcomes.
Among biological candidates, oxytocin — often called the “love hormone” — has received particular attention. Higher oxytocin levels are associated with more sensitive parenting, but how variation in the oxytocin system arises and affects caregiving remains incompletely understood. One promising mechanism is epigenetics: chemical modifications that change gene activity without altering the DNA sequence itself. DNA methylation, the addition of methyl groups to specific regions of a gene, can reduce gene expression and has been associated with personality traits and brain anatomy.
A team from the University of Fukui led by Prof. Akemi Tomoda explored whether methylation of the oxytocin gene (OXT) relates to maternal empathy and brain structure. Their study, published in Psychoneuroendocrinology, combined epigenetic measurements, structural brain imaging, and validated empathy assessments to examine links among OXT methylation, gray matter volume, and empathy in mothers.
The study included 57 Japanese mothers with at least one young child. Researchers measured DNA methylation of the OXT gene using saliva samples. They assessed brain structure using voxel-based morphometry (VBM), a neuroimaging method that quantifies gray matter volume across the whole brain. For empathy, they administered the Interpersonal Reactivity Index, which captures both cognitive and affective dimensions of empathy, including a subscale that measures Personal Distress — the tendency to feel distressed when witnessing others’ suffering.
Key results revealed a positive association between OXT methylation and Personal Distress: mothers with higher methylation of the oxytocin gene reported greater personal distress, a trait linked to more irritable or harsher parental responses. In parallel, higher OXT methylation correlated with reduced gray matter volume in the right inferior temporal gyrus. In short, greater epigenetic suppression of OXT was associated both with increased affective distress and with lower gray matter volume in a brain region implicated in social and emotional processing.
The researchers also tested whether gray matter volume in the inferior temporal gyrus mediated the relationship between OXT methylation and empathy. Their statistical analyses did not support a significant mediating effect, suggesting that while OXT methylation relates to both brain structure and affective empathy, the reduced gray matter volume in this region does not fully explain the link between epigenetic modification and heightened personal distress.
Prof. Tomoda commented that this study is the first to document a relationship between DNA methylation of the oxytocin gene and maternal empathy, and the first to associate that epigenetic variation with both empathy and structural brain differences. The work builds evidence for an epigenetic pathway connecting the oxytocin system to empathy-related traits and neural anatomy in mothers.
These findings contribute to a growing field called imaging epigenetics, which aims to connect epigenetic markers with brain structure and function to explain behavioral differences. Understanding how OXT methylation influences maternal affective responses may help clarify mechanisms underlying less sensitive or harsh parenting and could inform approaches to support healthy parent–child relationships and child development.
About this research
Source: University of Fukui
Contact: Press Office – University of Fukui
Image: The image is in the public domain
Original Research: Closed access. “Epigenetic modification of the oxytocin gene is associated with gray matter volume and trait empathy in mothers” by Daiki Hiraoka, Shota Nishitani, Koji Shimada, Ryoko Kasaba, Takashi X. Fujisawa, and Akemi Tomoda. Published in Psychoneuroendocrinology.
Abstract
Epigenetic modification of the oxytocin gene is associated with gray matter volume and trait empathy in mothers
Maternal empathy plays a critical role in parenting behavior and in children’s emotional development. While oxytocin has been linked to empathy, the epigenetic basis of oxytocin’s contribution to maternal empathy has been unclear. This study examined relationships among OXT gene methylation, empathy, and gray matter volume in a sample of 57 mothers of young children. Empathy was measured using the Interpersonal Reactivity Index, genetic methylation was quantified from saliva samples, and gray matter volumes were assessed by voxel-based morphometry across the whole brain. Results showed that higher OXT methylation correlated with increased Personal Distress (an affective empathy measure) and with reduced gray matter volume in the right inferior temporal gyrus. Mediation analysis did not find a significant indirect effect of inferior temporal gyrus volume on the link between OXT methylation and empathy. These findings provide empirical support for an epigenetic mechanism connecting oxytocin gene modification with structural brain variation and empathy traits in mothers, advancing our understanding of biological influences on parental behavior.