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Why Your Genes Aren’t Your Destiny


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At one time scientists believed our DNA held the key to preventing and reversing disease. But we now know that our environment—not our genes—is the primary driver of health and longevity.

why genes aren't your destiny
We have more control over our health and longevity than we realize. iStock.com/portishead1

The 20th century was the golden age of genetics. It ushered in the discovery of the double-helix structure of DNA, the polymerase chain reaction (PCR) method of amplifying DNA, and ultimately, the sequencing of the complete human genome.

Somewhat understandably, these remarkable discoveries led to “biological determinism,” the belief that human behavior and health is mostly—if not entirely—controlled by our genes. And it generated some pretty bold proclamations:

We now have the possibility of achieving all we ever hoped for from medicine.

Lord Sainsbury, Former UK Science Minister

Mapping the human genome has been compared with putting a man on the moon, but I believe it is more than that. This is the outstanding achievement not only of our lifetime, but in terms of human history.

Michael Dexter, The Welcome Trust

But it quickly became apparent that these heady promises weren’t going to pan out. Even Craig Venter, one of the first scientists to sequence the human genome, recognized the limitations of using genes to predict and prevent disease:

We simply don’t have enough genes for this idea of biological determinism to work.

Craig Venter, Chairman and CEO of J. Craig Venter Institute

We now know that genes account for about 10 percent of human disease.

So if our genes aren’t driving disease, what is?

The Exposome as the Primary Driver of Health and Disease

The “exposome” is a concept that was originally proposed by Dr. Christopher Wild in 2005. (1) It refers to the sum of all non-genetic exposures in an individual lifetime, starting from the moment of conception. It encompasses everything from the food we eat, to the water we drink, to the air we breathe, to the social interactions we have, to the lifestyle choices we make, to the health of our parents at the time of our conception.

In short, it’s the word scientists are using to describe the full range of environmental exposures that influence our health.

Genes may load the gun, but environment pulls the trigger.

The exposome has been broken down into the following three categories:

  • Specific external environment. This includes diet, physical activity, water, consumer and personal care products, lifestyle choices like smoking, infectious agents, chemical pollutants, etc. It also includes our environment at the earliest stages of our life, including our mother and father’s health at the time of our conception and gestation, the method of our birth, whether we were breastfed or not, and our early life bond with our mother and other social and psychological influences.
  • General external environment. This includes climate; urban vs. rural setting; traffic; our wider economic, social, and psychological influences including social status, education, financial status, and stress.
  • Internal environment. This includes internal biological factors such as metabolism, the microbiome, inflammation, hormones, and oxidative stress. (2)

The reason the exposome is important as a concept is that we now know it is the primary driver of human health and disease. If genes cause less than 10 percent of disease, it follows that the exposome—our diet, lifestyle, and environment—drive the remaining 90 percent.

In fact, recent estimates suggest that about 50 percent of early death worldwide is attributable to just a few environmental factors, including diet, indoor and outdoor air pollution, and active and passive cigarette smoking. (3)

The Epigenome: Where Our Genes and Exposome Meet

The “nature vs. nurture” debate—the question of whether our genes (nature) or environment (nurture) are more important to determining our health—has raged for decades. But the relatively simple distinction we’ve made over the years between genes and environment, as if they are separate and unrelated factors, turns out to be inaccurate.

According to Dr. Randy Jirtle:

The nature vs. nurture argument is rapidly proving to be irrelevant, because we’re finding that the two forces interact in highly specific ways that alter gene behavior.

Dr. Jirtle is a pioneer in the field of epigenetics. Epigenetics, which literally means “on top of” genetics, is the study of modifications to our genetic material that change the way genes are switched on or off, but which don’t alter the underlying genes themselves.

We used to think our DNA was like a template or a mold: if you poured raw genetic material into this mold 100 times, you’d get 100 identical copies. This is consistent with the philosophy of “biological determinism” that was en vogue right around the time the human genome was sequenced.

But a better analogy for genes might be a script for a theater production or film. Our genes are like the script, and the exposome and epigenome are like the production and performance. The script of Romeo and Juliet doesn’t change from one production to the next, but how it is produced and performed can vary dramatically depending on the director, cast, crew, set design, costumes, and other factors. If a script is terrible, even a great performance can’t save it. On the other hand, the best script in the world won’t matter with a terrible production.

This explains why identical twins are similar, but not the same. They are matched for genes, age, sex, pre-gestational (and often post-gestational) environment, so we’d expect their risk of having the same diseases to be very high if genes were running the show. Yet in most cases the discordance rates between twins for even highly heritable diseases like schizophrenia can be up to 50 percent. (4) In other words, if one identical twin has schizophrenia, there’s only a 50 percent chance that the other twin will have it.

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Dr. Francis Collins, director of the US National Institutes of Health, once summarized the relationship between genetics and the exposome in a single, pithy sentence:

Genes load the gun, but environment pulls the trigger.

Don’t get me wrong—genes do have a powerful influence on our susceptibility to disease, and there are situations where information about your particular genetic make-up can be useful. For example, there are genes (such as MTHFR, COMT, MTR, MTRR, etc.) that affect the methylation cycle, and mutations in these genes may lead to impaired detoxification, neurotransmitter metabolism, cellular energy production, and a range of symptoms such as depression, fatigue, and infertility. But in most cases, genetic predispositions will often only manifest in the presence of certain environmental factors.

The obesity epidemic is perhaps the clearest example of this. Our genes have not changed appreciably in the last 40 years, but during that time we’ve seen an explosion in the rates of obesity. This suggests that genetics are not the primary driver of obesity. However, we do know that there are genes that predispose some people to obesity more than others, and that not everyone is equally affected by exposure to the same environment. This suggests that genes do play an important role.

How to Fix Your Exposome

The recognition that environment, not genetics, is the primary driver of human health and disease carries with it a strong message of personal empowerment and responsibility. If our genes were the only determinant of our health, there wouldn’t be much motivation to optimize our environment. But since we know that the choices we make in our lifetime predict 90 percent of our risk of disease and early death, we have a strong reason to take action to improve our health.

But where do you start? With so many possible environmental influences, ranging from diet to chemical exposure to air pollution to personal care products, where do you get the biggest bang for your buck?

I believe that, for most people, the following four areas are the most important to focus on first:

  1. Diet
  2. Physical activity
  3. Sleep
  4. Stress management

We have an overwhelming amount of research demonstrating the influence these four areas have on our health. And I’ve also seen the greatest impact from focusing on them in my work with hundreds of patients.

This is why I created the 14Four last year. It’s designed to help people optimize their diet, physical activity, sleep, and stress management in just 14 days. I encourage all of you who’ve been procrastinating, or planning, or wishing, to try these 4 simple strategies for just 14 days.

When you join 14Four, you’ll also get access to our private Facebook support group, moderated by our fantastic Registered Dietitians (Kelsey & Laura).

Why make these changes as part of a group? Because research has shown that you dramatically increase your success at making consistently better day-to-day diet and lifestyle choices if you have social support. (5)

Click here to learn more about the 14Four challenge and join us in taking back your health!

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Join the conversation

  1. Great Article! I’ve grown tired and cross-eyed from reading all the information on methylation and experimenting with lots of supplements!

    But can 14Four be done if you have diet restrictions? I don’t think so 🙁 Taking methylfolate on a drs recommendation 2 years ago started a landslide and now I can no longer tolerate high histamine foods. I could before.

    • The diet is only one part of 14Four. You can adapt the recipes for your diet restrictions and focus on the other 3 areas: sleep, stress and movement.

  2. “According to Dr. Randy Jirtle:

    The nature vs. nurture argument is rapidly proving to be irrelevant, because we’re finding that the two forces interact in highly specific ways that alter gene behavior.”

    Always a false dichotomy, really, given that the human body is part of the environmental system and vice versa – rather than being an isolated actor striding a passive stage which has tended to be the scientific view in a philosophical sense.

  3. i already knew about epigenetics and i found your article very well put chris. i’m going to use it to explain to others what epigenetics are. i have so much brain fog that it is difficult to put my knowledge into words-so thanks!

  4. As I’ve been having IVs for cancer treatment in my naturopath’s office, I’ve been meeting other patients like me, who have serious health problems due to their genetic mutations.

    Most of us are normal weight, eat organic, Paleo diets and do everything possible to minimize exposome influences (and have been for a long time), but we are still dealing with serious illness. Yes, the exposome is important, but the rosy view that genes don’t matter too much is ridiculous for many of us. Genes matter, and doctors are beginning to be aware of how much.

    23andme can be empowering, and obviously, functional testing tells you what you’re dealing with at any point in time. But formulaic, eat Paleo answers simply do not begin to address the complexity of problems many of us face.

  5. Realizing environment hugely impacts disease is incredibly empowering. Diet can be considered environmental. SCD, used by many for healing, was just shown to increase F. prausnitzii for Crohn’s. F.prausnitzii is the most abundant gut bacteria belonging to the Phylum of Firmicutes, clostridial cluster IV, which seems to be reduced in IBD. Or at least those having more of it, fare better. F. prausnitzii produces high amounts of butyrate and anti-inflammatory compounds including antioxidants. Participants in the study had ~80% diet compliance, and the SCD microbiome remained despite a 30 day washout during which they ate whatever they wanted. IBD CROHN’S: SCD INCREASED MICROBIOME DIVERSITY BUT LOW RESIDUAL DIET REDUCED DIVERSITY, http://biomeonboardawareness.com/ibd-crohns-scd-increased-microbiome-diversity-low-residual-diet-reduced-diversity/

    The Dec 2014 “Advances in IBD” conference discussed CAM and IBD. SCD was one practice discussed, where disease activity indices and mucosal healing was shown for Crohn’s. Links to that PowerPoint are in: CAMS [ARTEMISIA, SCD…] & INTEGRATIVE MEDICINE BENEFITS GUT HEALTH, http://biomeonboardawareness.com/cams-artemisia-scd-integrative-med-benefits-gut-health/ The presenter, a pediatric GI, made the comment, “SO CERTAINLY THERE IS SOME PROMISE IN AT LEAST THINKING ABOUT THIS.” And she disclosed conflict of Nestle Nutrition and several pharmaceutical speaker/consultant commitments.

  6. You said it beautifully, Chris. I feel epigenetics is especially important when it comes to reproduction because optimizing our own genetics has a deep impact on the health of our offspring (and future generations).

    I have been doing tons of research on polymorphisms that affect fertility and incidence of miscarriage. My main emphasis to my clients is how important it is for our health to be optimal if we are to have optimally healthy children.

    Knowing your genetic profile can help you to take targeted action to compensate for polymorphisms that have begun to be symptomatic. Thanks for all your work.

    1. NO SALT.
    2. NO SUGAR.
    7. LAUGH.



  8. Thank you for this great information! I am a person who thought I was living life fine, but developed ulcerative colitis and chronic pain after an especially stressful time in my life. It turns out I am missing the SAMe component genetically, causing impaired detoxification. I am now paleo, very aware of what I put in and on my body, taking SAMe as well as other components to help my detox system, and doing infared sauna to get heavy metals out more quickly. My question is, once the gene expression has been turned on, can it be turned off, once I resolve my issues?

    • Hi, just a thought. vitalityherbsandclay.com is a web site owned by a ND, and master herbalist. He has a line of products of strictly herbal compounds and clays. His clay is called Sacred Clay and is a pyrophylitte clay, or dirt/lava clay. It’s the best of all clays and hardest to find. He found a site up by Crater Lake, Or. underneath a glacier.

      In 6 weeks at 1 tblsp. a day I lost 25 lbs. and didn’t think I had that much to loose, but he said this clay has a ton of negatively charged ions and grabs any and all positively charged ions in the toxins and pulls them out of the body, and the fat that was made by the body to hold them, goes to.

      It’s the fastest and most detox of all the clays, and the fastest detox I know of period. Heavy metals and all pathogens are gone from the body, or anything that is positively charged.

  9. Chris,
    I just got my results back for 23andme today. I do not know why people are so scared to get the test done, but I supposed a lot of people think nothing can be done and *would rather not know*.

    Knowing you have High Fructose Intolerance and consequentially removing fruit from your diet can save someone, while knowing you have OTC mutations and minimizing meat can save someone else.

    For me, I found out I am a fast metabolizer of coffee. Makes me happy xD

    Thanks for another great article.

    • I was just thinking about doing 23 and me, but when I went to their website they implied that, for legal reasons, they were now only telling you your ancestral results (of only limited interest) and giving you the raw data on the other stuff. Knowing that I have the variant for gene 123XYZ is useless, and I don’t foresee my going through my results and looking up every single gene on the internet. Did I misunderstand what they are doing? Is it still worthwhile?

  10. Thanks for this article! Perfect timing for things I’m working on, and I can really see how being a boomer (parents who smoked, Twinkies in the lunch box, etc.) had an impact on how my body is acting/reacting now.

  11. Dr Francis Collins was my genetics professor at Univ of Michigan Medical School many years ago. His saying then “The gene proposes, the environment disposes”.

  12. Thanks for this! I was just diagnosed with a homozygous gene mutation (C677T) and am working with a functional medicine doctor to correct what’s wrong. While I first and foremost trust in the Lord for my fate, I do find this article empowering as I know I do have the personal responsibility to make choices that can either help or hurt my health.

  13. Thanks for the article. I do miss however the importance of the microbiome. Some researchers, notably Dr. Alessio Fasano (well worth checking him out on youtube and here http://www.tenderfoodie.com/blog/2014/5/1/dr-fasano-on-new-gut-autoimmune-research-autism-clearing-up.html , argue that what makes us humans so different from other species is our micro-biome. I.e. not so much our genes but the infinite number of bacteria and microorganisms on and in our body sets us apart, also from one another. Obviously part of that is inherited, but if you eat unhealthy and do not move even if your had an ideal start you are going to suffer; still if you had a very good start in terms of genes and micro-biome you could tolerate much more before deteriorating. On the whole by the way, arguing what’s more important – heredity or environment – ends up telling that in determining surface length is more important than width or vice versa. Meaningless in a sense, it’s the interaction. As a neuropsychologist though I think that the importance of heredity including the heridity of the gut micro-biome and the brain/intelligence is underestimated in your article. There is plenty of evidence for example that your citation of the heredity of schizofrenia in twins is incorrect (it’s in fact much higher, at least that’s what I learned). My guess, fed by Fasano, is that the most important contributing factor is the diet (and the (changes in) gut micro-biome). So if raised apart and eating differently, then maybe. However, the most striking thing in identical twins is that their behaviour and preferences are also almost identical even if living apart.
    So I am not arguing against your advice but I think you underestimate the importance of the micro-biome (and the inheritance of that). And for that reason the paleo diet may not be the best choice for everybody.

    • Sorry, the figure of 50% maybe correct or it may be even significantly less as is argued here http://human-nature.com/nibbs/03/joseph.html
      However, my argument still holds: the nature – nurture debate will never be settled as it is the interaction that matters. AND we can only influence the environment. So best to focus on what we can change.

    • I have written and spoken about the importance of the gut microbiome at length, on this blog, on my podcast, in my book, and in numerous presentations and talks I’ve delivered. I also mentioned it as one of the important features of the “internal environment” category of the exposome. It is a crucial environmental factor, both because the expression of bacterial genes influences our own health, and because the composition of the microbiota also affects our own gene expression.

      The Paleo approach is an excellent choice *exactly* because of it’s impact on the microbiome, as this study clearly indicates. Paleo emphasizes fruits, vegetables, tubers, nuts, seeds, and other foods that feed the beneficial gut microbiota. All of our ancestors ate a “Paleo diet”, and their gut microbiota is the original human microbiota.

    • Do you really think other species don’t have their own microbiome??? They do. Do a little research on what’s been learned about the human microbiome and other animals’ microbiomes from the studies of non-human animals. It’s fascinating.

  14. It’s a shame a public figure like Angela Jolie wasn’t aware of this — or if she did, that she nonetheless chose to go under the knife.

      • She got more than mere “reduction”. So many celebrities seem to develop mental/psychological issues. Maybe it’s the smog in LA, or a combination of factors in their exposome.

  15. Well I’ve been saying this for years, genes are not destiny, just a roadmap. You choose your path, your genes adapt to the changing environment. The radical change in our diet over the last 100 years has lead us to this explosion of chronic disease. We can recover, the body has an incredible ability to withstand what we put into it. Give it what it needs and it will respond.

  16. Where did you take your 10% gene / 90% environment figure? (You don’t give any reference in the text.)

      • They give a few examples (type 2 diabetes, height) where only 10% of the variance was explained by known gene variants (and I didn’t bother to follow their references, so I am not sure if they really have the research to back up those claims). That doesn’t mean that the total genome explains only 10% of the variance in those specific examples, nor does it mean that the 10% figure extends to all diseases.

        • “Few doctors or researchers acknowledge
          that in the early 1900s there was an overall extremely low level of cancer
          in this country. Don’t believe anyone who says there was just as much
          cancer then as now, but it just wasn’t tracked. Physicians and the medical
          journals did track cancer rates at that time, and so did our government. One
          hundred years ago, only about 3% of us developed cancer! Yet cancer has
          skyrocketed to a current staggering 50% of the population today.”
          “There simply hasn’t been enough time for a “genetic mutation” to be
          passed to 50% of the population.”

          Some of the argument is intuitive.

      • Your reference says:

        “Unfortunately, genetics has been found to account for only about 10% of diseases, and the remaining causes appear to be from environmental causes.”

        But they don’t give any explanation or reference themselves.

        So, where does the 10/90 figure come from?

        It seems to me that it was simply made up, and you parroted it in your article.

  17. No question environmental factors are important and Chris your recommendations are sound but what if someone has gene variants in their methylation cycle (i.e. MTHFR, CBS, COMT, etc) which although will benefit from taking care of your environment can still cause massive issues. I.e. I have various SNP’s in the cycle and ate, exercised, slept and avoided stress exactly as you prescribe yet still suffered a list of negative health symptoms. One month after addressing methylation roadblocks with specific supplements and avoidance of certain (healthy) foods I’m asymptomatic for the first time in my adult life. So much so that I can eat plenty of grains, dairy, sugar if/when I want and have no issues. Certainly something I couldn’t do when I was simply controlling environmental factors.

    • I do use genetic testing in my practice, but I always accompany it with functional testing. To use your methylation example, I’ve seen people with mutations in methylation-related genes with no functional methylation issues (low folate derivatives, SAM, SAH, GSH, etc.), and I’ve seen people with functional methylation issues without significant mutations. Genetic information can be helpful for both diagnosis and treatment in some cases, but I don’t believe it should be used exclusively without the functional testing to back it up.

      Also, you mentioned that you ate, exercised, slept, and avoided stress as I prescribe. That’s great, but the exposome refers to environmental/non-genetic exposures **from the moment of conception**. It doesn’t just refer to what you’re doing now, but what you’ve done all of your life, and even what your mother and father were doing prior to and at the time of your conception, your gestational environment, etc. All of those influences have a huge impact on how your particular genes were programmed to express, so that someone else with your same genes who was born into a different environment would not have ended up with the same issues you have, despite having the same genes. That is the point of this article.

      • I have MTHFR 677 C/T and I cannot find any one practitioner who is specialized in treating this genetic mutation. I’m taking Methyl Guard from Thorne (3 capsules per day) and avoiding folic acid in my supplements, among other minor changes. If I have toxic overload, poor estrogen metabolism, heavy metals, etc, shouldn’t I address these? Do I need to detox and then treat MTHFR? I had Homocysteine level checked and it was excellent so that’s not an issue for me. Should I have heavy metal levels checked? Does acupuncture help? I also have the NET genetic mutation but the doctors seem to be ignoring this. I think if it showed up, I need to address it. It’s the norepinephrine transporter gene. Not sure if it means I have too much Nor, not enough, or just reuptake process is inefficient. If you could address all of these, I would appreciate it!

        Thanks, Susan

        • Susan, have you tried contacting Dr Ben Lynch.
          He’s built a whole careers, and developed a line of supplements (see Seeking Health HomoCystex Plus which I take) aimed at MTHFR mutations. There are a few other doctors who specialize in this too.

        • Part of the point of this article is that you don’t treat genetic mutations—you treat their effects. That is why functional testing to determine the downstream effects of a mutation is essential. A mutation of a gene does not necessarily imply dysregulation of that gene; it implies a decreased affinity for binding co-factors for the enzyme the gene codes for. This may, or may not, lead to dysfunction depending on a number of factors, including the person’s intake and absorption of those particular co-factors.

          What’s more, you have to look at all of the genes. A mutation in one gene might upregulate a particular pathway, while a mutation in another gene might downregulate that same pathway. If you only know about the one mutation, and make treatment decisions based on that alone, that’s not a good idea.

          This is why I have a problem with the services that have cropped up which make automated diet and supplement recommendations based only on genetic mutations, without looking at what is really going on functionally.

          Genetic testing can indeed be a powerful tool, but in my opinion it should always be combined with functional testing, i.e. testing the measurable effects, or lack thereof, of the mutation in question. To provide an example, MTHFR is involved in the conversion of 5,10-methylenetetrahydrofolate to a molecule called 5-methyltetrahydrofolate. It is also involved in the conversion of homocysteine to methionine. You can test for 5-MTHF and homocysteine levels, and doing that can give you a good idea of how the MTHFR enzyme is functioning.

    • Pls Matt, how can I get in touch with you? I am on the road of recovery with my SNPs trying different things but I have made just some difference. You said a month? That is amazing! Thank you.

  18. >>Genes may load the gun, but environment pulls the trigger.

    Then studying ones genes on 23andMe and similar services would be a waste of time and money!

    • Not when you combine it with functional testing. Then knowing which genetic mutations you have can be a helpful tool, but that data should never be used in isolation to make treatment decisions.

    • 23andme is not a waste of time. It is a tool. I recently had this test done. It showed I have the homozygous variant that puts me at high risk of hereditary hemochromatosis. No that doesn’t mean that I have the condition, but it alerted me to the possibility.
      Subsequent tests show that I do have the condition. Thanks to 23andme I have caught it early enough to avoid permanent tissue damage such as cirrhosis of the liver and a shortened life span.
      Another person might have the same genes but be perfectly fine.

  19. I didn’t see a more sensible way to communicate with you, so I’m doing it this way. I’m waiting for someone to write a really good take down of this asinine study: http://www.thelancet.com/journals/langlo/article/PIIS2214-109X%2814%2970381-X/abstract
    They argue that the global diet is getting worse, and measure various country’s intake of “good” and “bad” foods. PUFAs are “good,” meat is “bad,” so the Mongolians end up at the bottom of the pile, since they have not stopped eating the locally available meat and started importing large amounts of fish, veggies, and soy oil. Doh. If you’re going to measure global diet change, why not measure penetration of processed industrial foods?

    • Well right off the bat, the authors arbitrarily decided what was “good” nutrition and what was “bad” nutrition. Clearly, they don’t have a clue as to what good and bad is. They define salt as bad (totally false) and fish and vegetables as good (again, no proof of this). If you read “The Big Fat Surprise” it will change your views of good and bad. Essentially, good diets are whole, unprocessed foods without added sugar and bad diets are processed foods or foods cooked with processed vegetable oils and containing high amounts of sugar. If you go by that, Mongolians would finish near the top of the list.

      • I tried to make clear in my comment that I am already on the Good Calorie Bad Calorie/ Big Fat Surprise bandwagon. I wanted someone more skilled in reading studies than I am to do a more devastating job than I am capable of doing explaining exactly how lame this study is, and how completely insane their definitions were. And I wanted it to be someone with a wide readership, so that as much of the internet as possible can get organized rolling our eyes at them. The NY Times covered it, but didn’t have a comment option.

        • Well the assumptions of the study are based on a narrow and now proven false assumption of healthy diet, so the study itself now has to be regarded as useless.