Although a few traits — gender, race and hair color, for example — are controlled by a single gene and cannot be changed, most of our physical and biochemical characteristics are controlled by multiple genes. Our height and weight, metabolism, and most illnesses are affected by many different genes in concert with our environment.

The truth is, we all enjoy a tremendous opportunity to affect the expression of our genes — as well as our traits, tendencies and overall health — by improving both our physical environment and our cellular environment through more healthful diet and lifestyle choices.

There has been a great deal of excellent research that accentuates this point. In one Scandinavian study, for example, researchers assessed more than 44,000 pairs of identical twins to determine whether cancer was genetic. The result? Fewer than 10 percent of cancers could be traced to genetic predisposition; the rest were predominately environmental in origin, resulting from lifestyle choices such as diet and personal habits. (Only breast, prostate, stomach, lung and colon cancers showed a significant hereditary inclination.)

The same is true of other diseases. Let’s say you were born with a genetic tendency for heart disease. Meanwhile, you smoke, don’t exercise, eat poorly, gain weight and are under a lot of stress. Taken together, these factors strongly suggest that you are likely to develop heart disease at an early age. Yet, if you had the same genetic tendency for heart disease, but avoided smoking, exercised regularly, ate well, maintained your weight, and took steps to reduce and manage your stress, you would quite likely prevent heart disease from ever developing.

Or take the recent study in which Finnish researchers gave two groups of people with metabolic syndrome, or prediabetes, a slightly different diet. For 12 weeks, each group ate the same number of calories and the same amount of fat, protein, carbohydrates and fiber. The only difference? The first group had wheat, oat and potatoes as its carb source, and the second group had rye — which has very special properties because the body slowly absorbs it, and its phytonutrients help you lose weight and improve metabolism.

So what happened? The wheat, oat and potatoes diet activated 62 genes that increased inflammation and oxidative stress, worsened the blood-sugar balance, and generally amplified all the forces in the body that can lead to obesity, heart disease, cancer, diabetes and Alzheimer’s disease.

It was a 100 percent effect: No good genes were turned on. The rye diet, on the other hand, activated 71 genes that prevent diabetes, lower cholesterol, reduce inflammation and improve blood-sugar control — a 100 percent good gene effect.

Just imagine: If there were a drug that could turn off all the disease-promoting genes and turn on all the health-promoting, anti-aging genes, it would be a blockbuster. But you don’t see ads on television telling you to eat more whole-kernel rye bread!

Don’t Be Trigger-Happy

Most of our genes developed when we were eating a very different diet of whole, wild, fresh, real food and lived in a world without toxins like mercury and pesticides. In other words, our present-day genes were designed to thrive in a much more pristine world. Faced with present-day challenges — including a nutrient-deficient diet, a sedentary lifestyle and a profusion of environmental toxins — those same genes can become easily confused and disrupted.

Although much-ballyhooed genetic testing can be a helpful guide in understanding the origins and the risks of some chronic illnesses, we have to recognize that it is the interplay of many genes interacting with the environment and our daily choices that determines our health.

In reality, mutations in a single gene that we’re powerless to change cause less than 1 percent of all diseases, and these are rare disorders like cystic fibrosis and Tay-Sachs. We also know that there is nosingle gene for Alzheimer’s or depression or heart disease or cancer or autism. So we must give up the myth that our genes are entirely to blame. Instead, we must acknowledge that there are common variations in the symphony of our gene patterns that are integral to many chronic diseases — patterns that vary from person to person and are highly influenced by diet, toxins, allergens, infections and stress.

That’s actually wonderful news, because it means we can work to correct the environmental inputs and, in so doing, relieve the burden of suffering from so many chronic diseases. In future articles in this series, I’ll be offering lots of examples of how you can begin transforming your own health profile through better health habits and choices.

In the meantime, remember this: However your genetic gun might be loaded, you’re under no obligation to pull the trigger by making unwise choices. Nor should you just wait around passively accepting the suppression of symptoms that passes for “treatment” of many of today’s most common chronic health problems.