How to Overcome Your Genetics and Live Healthy

Dr. Frank Shallenberger, MD

August 24, 2020



Your mother died from breast cancer, so you’re concerned that you might get it.

Your father had Parkinson’s, which makes you more susceptible to it, right?

Whatever your family history is, modern medicine says you’re more at risk of coming down with this or that disease.

But here’s the problem. Disease is not the result of bad genes. Genetics play a role. But it’s not your genes that determine your health.

So let me tell you about a recent patient I had and a review article. They both prove my point.

The patient is another Frank. Frank is a 12-year-old boy who developed Crohn’s disease about 18 months ago. His case was severe. Even though his parents took him to the best doctors, he was steadily going downhill. It wasn’t until his parents took control and started treating him naturally that he actually started to recover. But that’s not why I am bringing his case up. This young man had an identical twin brother.

His brother is completely healthy. He has no signs of Crohn’s disease or any other health problem for that matter. But to the Mayo Clinic and other reputable sources that doesn’t make sense. They say that Crohn’s disease is a “complex system of genetic variations.” But if genetics causes Crohn’s, why didn’t this boy’s brother get it too? He has the identical genetics.

The answer, as I’ve already said, is because genetics play a relatively small role in why we get sick. And here’s a recent article that underscores this point.

Proof That Genetics Don’t Cause Disease

The authors of this article are from the Department of Nutrition at Norwich Medical School in the United Kingdom. They reviewed all of the current science and data on the use of genetic testing in medicine.

Here’s what they had to say: “Ten years ago, it was assumed that disease risk prediction and personalized nutrition based on genetic information would now be in widespread use. However, this has not transpired. The interaction of genetic make-up, diet, and health is far more complex and subtle than originally thought.”

This is not good news for Big Pharma and their plans to conquer disease with drugs. But it is good news for anyone who has a strong family history of disease. Because it means that no one has to get a disease simply because they have the genetics for it. The ball is still in their court.

I say it all the time, the best treatment for any disease is not to get it. But in order to prevent disease, you have to know what causes it. So the question is if genetics don’t cause disease what does? Identical twin studies answer that question.

Identical twin studies look at the risk of getting a disease for one identical twin when the other one already has the disease. Since identical twins have the same genetics this is a good way to find out just how big of a role genetics play versus other factors.

One such study looked at 31,848 male twins. Some of them were identical twins, and some were fraternal twins. Unlike identical twins, fraternal twins do not have the same genetics. Of these thousands of twins, 1,009 men in the group developed prostate cancer. Here’s what the researchers found.

If one of the identical twins developed prostate cancer, the other twin had a 27% chance of getting it. If one of the fraternal twins got it, the other twin had a 7% chance of getting it. When the researchers did the math, they found that the genetics for prostate cancer accounted for about 57% of the risk and “environmental influences” accounted for 43%. This is hardly a commanding position for genetics causing prostate cancer.

Other twin studies have looked at the impact of genetics for breast cancer. The results show that 3 out of every 100 breast cancers are due to genetics. The other 97 are caused by environmental and lifestyle factors. What about diseases other than cancer?

A Danish study looked at 77,885 twins. They compared the chance of getting type-2 diabetes between fraternal and identical twins. If there was a big genetic influence on type-2 diabetes, you would expect that the identical twins would have a much greater risk. Instead there was no increased risk at all. In the case of developing type-2 diabetes, genetics plays almost no factor.

How about Alzheimer’s? Researchers at the Department of Psychology, University of Southern California looked at 392 twin pairs in which one of them had Alzheimer’s. Some were identical and some were fraternal. They determined that the genetic risk for getting Alzheimer’s was somewhere between 58-79%. In this disease, genetics plays a strong role, but by no means is it the sole determining factor.

What About Parkinson’s?

Doctors at the Parkinson’s Institute in Sunnyvale, California looked at 250 twins with Parkinson’s disease whose brothers were free of the disease. Again, some were fraternal and some identical twins. They found that the likelihood of developing Parkinson’s disease was the same in both the identical and the fraternal twins. Their conclusion from the study was, “Genetic factors do not play a major role in causing typical Parkinson’s.”

Here’s another common age-related disease: osteoarthritis. Researchers at the Department of Rheumatology at St. Thomas’ Hospital in London studied 130 identical and 120 fraternal female twins aged 48-70. They X-rayed the joints in their fingers, hands, and knees to see if there were any signs of osteoarthritis. They then analyzed the results to see what role genetics played.

The researchers found that on average there was about a 50% influence from genetics. That means that the effect of genetics was no greater than the effect of lifestyle factors. I could go on all day with these studies, but let me just finish with macular degeneration.

This study came out of Harvard. The doctors examined the eyes of 210 identical twins and 181 fraternal twins. Once again, they found that the effect of genetics was about 50%. They pointed out that, “Environmental factors unique to each twin also contribute to the occurrence of this disease.”

So when you add it all up, it seems like the risk of developing any disease is roughly about half genetic and half lifestyle. Or to put it another way, your risk for a disease is 100% based on how your lifestyle matches up with your genetics. And the sobering conclusion is that no matter what your genetics are, the defining factor for whether or not you get a disease is not who your parents were, but how you live your life.

Adelle Davis, who was an author and nutritional pioneer in the ’50s and ’60s, said it best. “As I see it every day, you do one of two things: build health or produce disease in yourself.”

We have it in our own power to stay well and avoid all the misery and expense of disease. But as I have said before, it is not always easy to do by yourself. You will probably need to have a good alternative-minded practitioner to work with. So find one. And you will have to be somewhat disciplined. I hope that you would rather give something up that you like but is harmful, than indulge it only to become sick later.

Focus On Your Lifestyle

That means paying attention to what you eat, the supplements you take, the hormones you replace, regular exercise properly done, detoxification if you need it, and letting go of stress. I have written about these things before in Second Opinion, and will continue to update you as new remedies emerge. And my book, Bursting With Energy, also describes a great game plan.

Twin studies point out that just because you may have the genetics for a disease does not mean you have to get it. So don’t give up on making the healthy changes you need to make as though you were 100% destined to get the disease. You have every bit as much control over your future as your genetics.


Gatz, M., C.A. Reynolds, et al. “Role of genes and environments for explaining Alzheimer disease.” Arch Gen Psychiatry. 2006 February;63(2):168-74.

Minihane, A.M. “The genetic contribution to disease risk and variability in response to diet: where is the hidden heritability?” Proc Nutr Soc. 2012 November 21:1-8; Mayo Clinic Staff. 2005. “Crohn’s disease.”

Page, W.F., M.M. Braun, et al. “Heredity and prostate cancer: A study of World War II veteran twins.” Prostate, Volume 33, Issue 4, pages 240–245, 1 December 1997.

Petersen, I., M.M. Nielsen, et al. “No evidence of a higher 10 year period prevalence of diabetes among 77,885 twins compared with 215,264 singletons from the Danish birth cohorts 1910-1989.” Diabetologia. 2011 August;54(8):2016-24.

Seddon, J.M., J. Cote, et al. “The US twin study of age-related macular degeneration: relative roles of genetic and environmental influences.” Arch Ophthalmol. 2005 March;123(3):321-7.

Spector, T.D., F. Cicuttini, et al. “Genetic influences on osteoarthritis in women: a twin study.” BMJ. 1996 April 13;312(7036):940-3.

Tanner, C.M., R. Ottman, et al. “Parkinson disease in twins: an etiologic study.” JAMA. 1999 January 27;2

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