Familial and environmental influences on bone growth from 11-17 years

The influences on bone growth of familial factors, nutrition and physical a ctivity are described in a cohort of 108 children (56M, 52F). Distal forear m bone width, mineral content and volumetric density, anthropometry, pubert al status, nutritional intake and physical activity were measured at ages 1 1, 13, 15 and 17 y. Parental forearm bone status was also determined. Both mothers' and fathers' bone variables were significant predictors of the res pective children's bone variables, but heritability estimates were greater between mothers and their children than between fathers and their children. By age 17 y boys had attained 101%, 85% and 89% of their fathers' height, bone mineral content and volumetric density, respectively; girls had attain ed 103%, 95% and 98% of their mothers' height, bone mineral content and vol umetric density, respectively. There were no consistent associations among nutrient variables and bone status or rate of change in bone status. Howeve r, there was a significantly greater increase in bone mineral content and d ensity from 11-17 y in those girls with consistently high calcium intake. T here were no significant correlations between physical activity and bone va lues or rate of change of bone values. Age, gender, pubertal status, height , weight and parental bone values accounted for 80%, 71% and 49% of the var iance of bone mineral content, bone width and volumetric density, respectiv ely and 52%, 55% and 58% respectively of the variance of change in these va riables. After age, gender, sexual maturity and body size, heritability acc ounts for the greatest variance in bone values through adolescence.