EXAMPLE 7 Obesity in mothers and daughters

What causes obesity in children? Inheritance from parents, overeating, lack of physical activity, and too much television have all been named as explanatory variables.

The results of a study of Mexican American girls aged 9 to 12 years are typical. Researchers measured body mass index (BMI), a measure of weight relative to height, for both the girls and their mothers. People with high BMI are overweight or obese. They also measured hours of television watched, minutes of physical activity, and intake of several kinds of food. The result: the girls’ BMIs were weakly correlated with physical activity (r = −0.18), diet, and television. The strongest correlation (r = 0.506) was between the BMI of daughters and the BMI of their mothers.