Body weight in adolescence and adulthood may result from the interplay between individuals' genetic characteristics and the social context in which they grow up, such as family socioeconomic status (SES). However, evidence on the interaction between genetic propensity for high body mass index (BMI) and family SES remains inconclusive. This study investigates whether genetic associations with BMI differ among individuals from high-SES versus low-SES families and whether these associations vary ac