Spousal resemblance in the Canadian population: implications for the obesity epidemic.

OBJECTIVE: To determine the extent of the spousal resemblance for adiposity and leanness in the Canadian population.
DESIGN: Cross-sectional population survey.
METHODS: The sample comprised parents and offspring from 1341 families (n=4023) of the Canada Fitness Survey. Indicators of adiposity included the body mass index (BMI) and the sum of five skinfolds (SF5). Both offspring and parents were ranked by their BMI and SF5 percentile position in the population using the entire Canada Fitness Survey database (n=15 818).
RESULTS: Pearson correlations indicated significant spousal resemblance for both BMI (r=0.14; P<0.0001) and SF5 (r=0.13; P<0.0001). However, the magnitude of the spousal correlations varied by the adiposity status of the offspring, with spousal correlations tending to be stronger in parents of lean or obese children and lower among parents of 'average' children. Bivariate histograms indicated that among lean (<or=5th percentile) and obese offspring (>or=95th percentile), the parental pairs tended to cluster among the lower and higher percentiles of adiposity, respectively.
CONCLUSIONS: There are spousal similarities in adiposity, particularly among parents of lean or obese offspring in the Canadian population. The degree to which these similarities are due to a loading of spouses with genes predisposing to obesity or a shared household environment cannot be determined from the present study. However, these results are compatible with the notion that genes and mutations predisposing to obesity are more prevalent among obese parents while those for pronounced leanness are more prevalent among lean parents.