I think that in large part it is due to genetics (as your examples illustrate). But my view is also that using some things to excess can shorten a life, and in any case will certainly contribute to a less "able" and lower quality of life.
My mother smoked to her end at the ripe old age 89. But as compared to her older sister and her two older sisters-in-law, none of whom smoked past the 1960's, she was frail, less able to be physically active, prone to TIA's. Similar comments apply to excessive drinking.
I've observed older relatives who were sedentary and their last years were not very fulfilling to them, I think, due to limited mobility from disease or excess weight, or lack of cardiovascular stamina and muscle strength.
So, while genetics is a big factor, I believe that to enjoy a good quality of life one should not over-indulge in food, alcohol, smoking, and should maintain some type of an active lifestyle (mild exercise, etc).