Which statement is correct about childhood obesity?

A) Heredity is an important factor in the development of obesity.
B) Childhood obesity in the United States is decreasing.
C) Childhood obesity is the result of inactivity.
D) Childhood obesity can be attributed to an underlying disease in most cases.

Heredity is an important fact that contributes to obesity. Identical twins reared apart tend to resemble their biologic parents to a greater extent than their adoptive parents. It is difficult to distinguish between hereditary and environmental factors. The number of overweight children is increasing in the United States. Inactivity is related to childhood obesity, but it is not the only component. Underlying diseases such as hypothyroidism and hyperinsulinism account for only a small number of cases of childhood obesity.