Neural responses to socioemotional information are more similar among siblings and relate to social competence

Socioemotional skills are fundamental to children’s well-being and development, yet theneurodevelopmental processes through which familial relationships contribute to these skillsremain poorly understood. While socioemotional skills are partly heritable, they are also shaped bysocial learning through interactions with others, including siblings. Sibling relationships representone of the earliest and most enduring social contexts throughout development and provide avaluable context for investigating how familial relatedness is reflected in children's neuralprocessing of socioemotional information. However, little is known about whether siblings exhibitsimilarities in these neural responses and how such similarities relate to socioemotional behavior.In this study, we investigated whether sibling dyads show greater similarity in neural responsesduring socioemotional processing than unrelated child dyads and whether such neural similarity isassociated with socioemotional functioning. To assess this, 120 children (6-14 years), including 39sibling dyads, completed a naturalistic fMRI movie-watching task designed to elicit socioemotionalresponses. Results showed that sibling dyads exhibited greater whole-brain functional neuralsimilarity during socioemotional processing than unrelated children across the whole brain. Region-of-interest analyses further revealed greater functional neural similarity among siblings acrossseveral prefrontal, temporal, and limbic regions, including the left ventromedial prefrontal cortex(vmPFC). Moreover, greater similarity in left vmPFC responses, a region implicated in socialcognition, was associated with higher levels of socially competent behavior in both sibling andunrelated dyads, suggesting that neural similarity may be particularly pronounced among childrenwith higher social competence. These findings highlight sibling relationships as an informativecontext for investigating familial similarities in neural responses to socioemotional information andtheir associations with socioemotional behavior during childhood.