But what's found to be equally true is that the positive lifestyle choices we make -- most notably, eating right and exercising -- may have just as powerful an effect on our genetic makeup. Two recent studies illustrate this point. One found that eating well can "turn off" the genes that put one at higher risk for heart problems; the other showed that exercise can persuade stem cells to become bone and blood cells rather than fat cells. Each helps us see just how lifestyle variables work at the genetic level to modify our risk.

YOU (AND YOUR GENES) ARE WHAT YOU EAT

In the first study, people who ate more raw fruits and vegetables had a reduced risk of heart disease, even if they carried copies of the gene that increases one's risk for cardiovascular disease. The researchers divided groups of participants according to the type of diet they ate. They dubbed the diets as follows: a typical "Western" diet included more salty and fried foods, meats, eggs, and sugar; the "Oriental" diet consisted of more soy, pickled foods, eggs, and leafy greens; and the "Prudent" diet, contained more raw fruits and veggies, leafy greens, nuts, and dairy. People who were genetically at the very highest risk of having a heart attack (they had two copies of the specific genes associated with heart attacks) had about double the heart risk if they ate a diet lacking in fruits and vegetables, compared to people who ate a prudent diet.

The study illustrates vividly how eating well will not only help you feel better in an immediate way, but it could actually alter your genes and reduce risk to your heart in a long term way.

EXERCISE CAN SWAY THE FAT(E) OF CELLS

Exercise is the other piece of advice that we hear over again. It is strongly linked to a variety of health benefits from heart and vascular health, to warding off Alzheimer's, to extending lifespan. But now researchers are beginning to show that exercise may function, at least in part, by affecting the expression of our genes.

Certain types of stem cells can "choose" how they differentiate, and exercise and environmental factors can actually determine the direction that cells take early in their development. When mice ran on a treadmill for as little as an hour three times a week, the exercise induced these stem cells to become blood-producing cells of the bone marrow, rather than fat cells.

The stem cells of sedentary mice in this study were much more likely to become fat cells. "Some of the impact of exercise is comparable to what we see with pharmaceutical intervention," says author Gianni Parise in a university press release. "Exercise has the ability to impact stem cell biology. It has the ability to influence how they differentiate."

If exercise can influence how stem cells differentiate into mature cells, it is certainly possible that exercise also works on the genetic level as it influences our risk for certain diseases. More research will be needed to map out the molecular changes that exercise brings about. Again, since the evidence is overwhelming that exercise does reduce our risk for physical and mental health problems, it certainly won't hurt to put on your walking shoes and get moving.