Heredity v Environment
The question of how large a role heredity plays in health is a vital one, since if health is determined primarily by genetics, then there isn't much point in improving an environment factor like nutrition. While it may be convenient to blame everything on one’s heredity, I believe it's role is overstated, especially in relation to modern diseases like cancer, diabetes, heart disease and obesity.
It's not unusual for a nation to have very low rates of degenerative diseases, until they start shifting their natural diets toward western style depleted foods. When they do, their rates of heart disease, cancer, diabetes, and obesity all rise rapidly and dramatically, often within just 15 to 30 years. The genetics of a nation don't change in that short a time. It's also true, that while some diseases may seem to be the work of heredity, remember that environmental factors like dietary and lifestyle habits are passed down to children as well.
Obviously genetics does have some influence on health, but while your heredity may tilt you towards an illness, rarely is it enough alone to condemn you. It usually just means you have less room for error, so it may take less cigarettes to give you lung cancer, or less junk food to give you a heart attack. It's environment factors like nutrition, exercise, proper sleep and reducing toxin intake that have the greatest impact on health. The choices you make matter, the power is in your hands. Use it wisely.
Yours in Health and Happiness