Objective: To investigate the familial resemblance of 7-year changes in body mass and adiposity among Canadian families. Research Methods and Procedures: The sample consisted of 655 women and 660 men from 521 families who participated in the Canada Fitness Survey in 1981 and the follow-up Campbell's Survey in 1988. Indicators of baseline and 7-year changes in body mass and adiposity included body mass (kilograms), body mass index (BMI; kilograms per square meter), sum of five skinfolds (SF5; millimeters), and waist circumference (WC; millimeters). The data were adjusted for the effects of age and sex, and the change scores were adjusted for baseline levels. A familial correlation model was used to determine the heritability of each phenotype using maximum likelihood techniques. Results: Significant familial resemblance was observed at baseline and for 7-year changes in all phenotypes. At base-line, moderate heritabilities were observed [body mass: heritability coefficient (h2) = 56%; BMI, h2 = 39%; SF5, h2 = 41%; and WC, h2 = 39%], whereas values were attenuated for each change score except for WC (Δbody mass, h2 = 23%; ΔBMI, h2 = 14%; ΔSF5, h2 = 12%; and ΔWC, h2 = 45%). Discussion: Changes in body mass and adiposity signifi-cantly aggregate within families over 7 years. However, baseline values are characterized by higher heritability levels except WC. The significant heritabilities observed for change scores suggest that lifestyle, transient environmental factors, and possibly age-related gene effects are important determinants of changes in body mass and adiposity.
- Body fat
- Canada Fitness Survey