["Regular physical activity (PA) in young needs to be promoted to prevent obesity and subsequent diabetes. Influences of parental PA on adolescents' activity level have been studied with discordant results and the effect of socioeconomic status (SES) on these relationships is not clarified.", "Cross-sectional population-based survey of about 3000 12-year old French students and their parents. Familial associations were assessed with logistic regression models taking into account SES and children's and parents' corpulence. Sport involvement and sedentary behaviors were assessed by standardized questionnaires filled out separately by children and parents, the latter also reporting their educational data and family income tax.", "Participation in structured PA outside school was higher for boys (74%) than for girls (58%, p<10-5) and a high sedentary behavior (watching television, playing computer/video games and reading > or =2h/day) was observed in one-third of the sample, both in boys and in girls. Children were more likely to participate in structured PA outside school when both parents practiced sport as compared to neither parent practicing it, with an odd ratio OR (95%CI) of 1.97 (1.4-2.8) for boys and 1.56 (1.2-2.1) for girls. Familial associations of inactivity were significant for boys only. A greater percentage of adolescents had a high level of sedentary behavior when both parents versus no parents watched television > 2h/day (OR 1.95 (1.52.6)). Parent-child physical activity relationships were not modified by the family SES or the children's or parents' weight status."] Do parent-child physical activity relationships in 12-year old French students depend on family socioeconomic status?