What is the role of behavioral and environmental factors in group differences in the prevalence of disease?
Behavioral and environmental factors play enormous roles in the causation of common diseases. It is estimated, for example, that one-third of U.S. cancer deaths can be attributed to tobacco use, while another one-third are caused by dietary factors. Mortality due to coronary heart disease has decreased by more than 50 percent during the past 50 years because of improvements in diet, exercise, and medical treatment. Meanwhile, the incidences of obesity and type 2 diabetes have increased dramatically and threaten to reverse some of the progress made in preventing heart disease and other ailments. Considering these statistics, it is likely that non-genetic factors are far more important than genes in determining susceptibility to common diseases. The prevalence of most common diseases varies among populations. Hypertension is approximately 50 percent more common among African-Americans than European-Americans, and type 2 diabetes is seen in nearly half of Pima Native American adults. Agai
