Myth #2: Your fate is already sealed
You often hear this kind of fatalistic remark from people whose parents died young of heart attacks or cancer: “What’s the point of jogging and eating broccoli if my lousy genes are going to kill me anyway?” Furthermore, each passing week seems to bring news that scientists have discovered yet another “disease gene.” If our health destinies are preprogrammed, does it really matter whether we take care of our bodies?
In short, yes. The so-called breast cancer gene, BRCA1, offers a good example. There’s no doubt the gene is powerful: Some 60 to 80 percent of women who have a mutation of this gene will develop breast cancer as compared to 13 percent of women who don’t have the mutation. But that means that as many as 40 percent of women who inherit a BRCA1 mutation never develop breast cancer, suggesting that perhaps their lifestyle choices give them some protection.
What’s more, scientists believe that the majority of cancer cases are not caused by inherited bad genes. Swedish researchers looked at the incidence of various cancers among nearly 45,000 sets of twins and concluded that “genetic factors make a minor contribution to susceptibility” to most forms of the disease. The evidence clearly shows, they stated, that the environment a person lives in has by far the greater influence on cancer risk.
The same scenario seems to hold true for other diseases that can rob you of years. Imagine a pie chart representing all the factors that influence how long you will live. Many studies suggest that the genes you inherited from your parents make up only about one-third of the pie, and maybe less. The other items in the pie include diet, physical activity level, and personal habits, such as tobacco use and alcohol consumption. In other words, you can’t change your DNA, but what makes up the rest of the pie is largely up to you.