WebMD has interesting article suggesting our behavior can influence how are genes act. According to research by Dean Ornish people can change how certain genes perform by making modest adjustments to their life style. Ornish found that by engaging in exercise and eating a more low-fat diet "more than 500 genes changed the way they worked." More specifically, he found that some tumor-suppression genes became more active, while other genes with negative effects — including some cancer-promoting genes — were turned off when people engaged in a healthier lifestyle.
I especially liked this quote from Ornish, "People say, ‘Oh, it is all in my genes, what can I do?’ That’s what I call genetic nihilism." Undoubtedly, many people do subscribe to the idea that our genes determine our fate. If, however, Ornish’s findings prove to be true, it will dispel that idea and will require people to unlearn the idea that while "genes may be our predisposition, they are not are fate."