As a Doctor told my brother when he was discussing heredity versus non-heridity issues in predicting how senior years cardiovascular disease will impact your longevity:
(Paraphrase) Keep in mind that while fish oil, exercise, diet and controling blood chemistry play a part in balancing your genetic disposition to cardiovascular disease, the genetic predisposition will still contol 85% of the advancement with controlable measures accounting for 15%.
Heredity is an important factor, perhaps, as your doctor says, the most important in the case of cardiovascular disease. However, the disparity among the states and among different nations is a diet and lifestyle issue.