Your genes influence many aspects of your health, from how much you weigh to your risk of certain diseases. But your DNA sequence is only one part of the picture. Your environment and the choices you make about your lifestyle can alter how your genes behave — without actually changing your genetic makeup — through the epigenome. The epigenome consists of various chemical compounds that attach to your DNA and tell your genes what to do.

For example, factors such as diet, physical activity, stress and toxin exposures can cause changes to the epigenome that turn certain genes "on" or "off." These changes may increase your risk of certain diseases. But changes to the epigenome aren't necessarily permanent. The epigenome can continue to change throughout your lifetime, and a healthy lifestyle may help reverse unfavorable changes. In fact, lifestyle choices seem to be more important for your overall health than your genetic makeup.

Take the impact of fitness, for example: Physical activity has been shown to reduce the influence of genetic risk factors for obesity. In adults who have a common obesity-linked gene profile, active adults have a 30 percent lower risk of being obese than those with the same gene profile who aren't active.

Much research is underway to help us better understand the epigenome and how it affects human health. Fortunately, what we do know appears to reinforce the benefits of healthy habits that include eating well, getting regular exercise and managing stress.