Background Clustered obese parents and children are prevalent, but there is little knowledge about whether and how child–parent resemblance varies by sociodemographic groups.

Methods This paper used nationally representative data from the National Health and Nutrition Examination Survey III (NHANES: 1988–1994). We matched 4958 parents with 6765 children aged 2–16 years old for whom we had complete data on body mass index (BMI), overweight and obesity status. Correlation coefficients and κ statistics between parents’ and children's BMI and body weight status were calculated for different sociodemographic groups. Multivariate linear and logistic regression models were fit to study the child–parent resemblance and socioeconomic and demographic differences in the resemblance.

Results The child–parent correlation coefficients for BMI were greater in Caucasians than in minorities and greater in groups with higher socioeconomic status. The mother–child resemblance in BMI was negatively associated with child age (p<0.001). The mother–daughter resemblance in overweight was significantly lower in non-Hispanic blacks (OR=0.53, 95% CI (0.36 to 0.78)) and Mexican Americans (OR=0.58, 95% CI (0.36 to 0.93)) than in Caucasians. The father–child resemblance in overweight was significantly lower in high school graduates compared with those with less-than-high-school-graduate fathers (OR=0.53, 95% CI (0.37 to 0.77) for father–son dyads and OR=0.69, 95% CI (0.50 to 0.96) for father–daughter dyads). Similar results were found for parent–child resemblance in obesity.

Conclusions Child–parent resemblance in body weight status exists across sociodemographic groups in the USA, but it varies by demographics and socioeconomic status.