BACKGROUND/OBJECTIVES:Although there are some studies on familial clustering of metabolic risk factors, there are few on clustering of diet and physical activity. The aim of this study was to identify the extent of familial clustering of weight status, diet and physical activity in urban and rural families in South India. SUBJECTS/METHODS:Anthropometric, dietary and physical activity data were obtained for 325 offspring aged 8-21 years and both their parents from urban and rural South India. However, 294 single offspring and their parents were used for analysis. Body mass index (BMI) was computed and individuals categorized as normal, underweight and overweight/obese. Diet was assessed using food frequency questionnaires and physical activity using physical activity questionnaires. RESULTS:Offspring BMI correlated significantly (P<0.001) with the BMIs of both parents (r=0.35, P<0.001). Percent protein, carbohydrate, total fat and saturated fat intakes were significantly correlated (P<0.001) between offspring and parents. Offspring physical activity level (PAL) correlated significantly with the mother (r=0.26, P<0.001), but not the father. A two-step cluster analysis revealed two distinct clusters: obesogenic and nonobesogenic. The obesogenic cluster, which consisted of 83% of families with at least one parent or offspring overweight, had significantly higher intakes of fat, saturated fat and higher sedentary activity levels but lower carbohydrate intakes and sleep duration (all P<0.001) among both offspring and parents. CONCLUSIONS:Diet, physical activity and BMI of children, adolescents and young adults in India is associated with parental behavior. Health promotion aimed at reducing obesity in these groups should address familial issues.