Dr Caroline Leaf and the matter of mind over genes

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I think I might have to throw away my genetics textbook.

I was always taught that genes were the main driver behind health and disease, and I always thought it was a pretty good theory.

But not according to Dr Caroline Leaf, communication pathologist and self-titled cognitive neuroscientist, who said on her social media feeds today, “Our health is not controlled by genetics – our health is controlled by our mind.”

Taking her statement at face value, she appears to be saying that genes have nothing to do with our health. Dr Leaf has made some asinine statements in the past, but to suggest that genes are irrelevant to human health seemed so stupid that no one in their right mind would suggest such a thing.

Perhaps I was taking her statement the wrong way? I wanted to make sure I didn’t jump to any rash conclusions about Dr Leaf’s statement, so I pondered it at length. Could she be referring to ‘control’ in the absolute sense? How much control do genes have on our health? What about the mind?

After deliberating for a while, I still came to the conclusion that Dr Leaf’s statement was nonsense.

Unfortunately, Dr Leaf’s statement is, like so many of her previous Facebook memes, so vague as to be misleading. The meaning of ‘health’ and ‘controlled’ could be taken so many ways … which part of our health? How much regulation constitutes ‘control’? What about genetics?

Looking at her statement in more depth, it becomes clear that no matter which way Dr Leaf meant it, it’s still wrong. For example, all of human health is controlled, in part, by genetics. That’s because life itself is controlled by genetics. The human genome provides a blueprint for the construction of all of the proteins in all of the cells in our entire body. The expression of those genes determines exactly how our body will run. If the genes are wrong, if the translation of the gene code into a protein is wrong, or if too much or too little of a protein is made, all determines whether our body is functioning at its optimum level or not.

The stimulus for the expression of our genes is influenced by the environment in which we live. If I go out into the sun a lot, the UV light triggers my skin cells to make the protein melanin, which makes my skin go darker and helps to provide some protection against the damaging effects of the UV light.

While the environment plays a part of the expression of some genes, it’s wrong to say that genetics doesn’t control the process. If I go into the sun too much, I risk developing a melanoma, because the sun damages the genes in some of my skin cells, causing them to grow without control.

Genes are still responsible for the disease itself. Sometimes the trigger is from the environment, sometimes it’s not. There are some people with genes for melanoma who don’t need an environmental trigger, because they develop melanoma on skin that’s exposed to very little UV light, like the genital skin.

So fundamentally, even taking the environment into account, our health is controlled by our genetics.

The other part of Dr Leaf’s meme is also wrong. Our health is not controlled by our mind. Our genes are influenced by “the environment”, which according to the seminal paper by Ottman, “The environmental risk factor can be an exposure, either physical (e.g., radiation, temperature), chemical (e.g., polycyclic aromatic hydrocarbons), or biological (e.g., a virus); a behavior pattern (e.g., late age at first pregnancy); or a “life event” (e.g., job loss, injury). This is not intended as an exhaustive taxonomy of risk factors, but indicates as broad a definition as possible of environmental exposures.” [1]

Even if one considers the mind as part of the sub classification of “a behavior pattern”, it’s still pretty clear that most of the factors that make up our environment are not related to our mind at all but are related to the external world, of which we have minimal or no control over. Sure, we make choices, but our choices aren’t truly free. They’re constrained by the environment in which we find ourselves. In the same way, our mind may have some tiny influence on our health, but only insofar as our environment and our genes will allow.

When it all boils down, this meme of Dr Leaf’s is rested on her foundational presumption that our mind can control matter, a very strong theme throughout her most recent book [2], but which is still preposterous. Our thoughts are simply a function of our brain, which is in turn determined by the function of our nerve cells, which is in turn a function of our genes and their expression.

Our mind doesn’t control matter. Matter controls our mind.

I can keep my genetics textbooks after all.


  1. Ottman, R., Gene-environment interaction: definitions and study designs. Prev Med, 1996. 25(6): 764-70 http://www.ncbi.nlm.nih.gov/pubmed/8936580
  2. Leaf, C.M., Switch On Your Brain : The Key to Peak Happiness, Thinking, and Health. 2013, Baker Books, Grand Rapids, Michigan:

3 thoughts on “Dr Caroline Leaf and the matter of mind over genes

  1. Dear Dr,

    When you state that “matter controls our mind” how is that reconciled when the Bible declares ” as a person thinks so is he”. If my thinking is fixed to a material function then am i not a pre determined engineered system beholden to a mechnical closed loop system? One could well tweak it with material oil changes so to speak, but ultimately i am grounded by genetics and the material closed loop? Am i not pre determinely stuck? I am also trying to reconcile your post when we are made in the image of a conscious being outside of time space and matter with a free will to have a non determined choice of life and death – to chose a relationship or not [with others and or God], how can that be reconciled when matter is determining my choices? I appreciate the metaphysics are beyond the material sciiences and so the blurring of lines ocurrs, but if i hold to the world view that there is a Logos, beyond time space and matter and i am created in that being’s image then my physical condition does not pre determine my personhood: volition, emotion, thought?

    • Hi Benjamin, thanks for that very thoughtful and important question.

      I think the short answer is that we do not have free will, but constrained will.

      It’s not that we lack capacity to make any choices, but that those choices are constrained by our genetics, past experience, learning, and priming. Genetics influence how we perceive our world and how we interpret it through our personality and physiology. Then our brain decides on the best course of action based on how it predicts the value for each possible action, which is partly determined by our own unique collection of memory and prior learning. Most of this is done unconsciously, and probably significantly influenced by unconscious cues in the environment through priming. There are lots of scientific papers that discuss the neurobiology of volition if that is something you’re interested in. I’d suggest that you start with Haggard, P., Human volition: towards a neuroscience of will. Nat Rev Neurosci, 2008. 9(12): 934-46 doi: 10.1038/nrn2497 and go from there. I discuss volition in my book as well, which you can download for free from Smashwords (https://www.smashwords.com/books/view/466848).

      I think there are also some key phrases that you make in your statement that may also help answer your question. We are made in God’s image, true. But the Hebrew word for “image” refers to “a shadow, an image/likeness (so called from its shadowing forth)” http://www.blueletterbible.org/lang/lexicon/lexicon.cfm?Strongs=H6754&t=KJV. So we are like him but that doesn’t mean that we share all of his properties. God is outside of the space-time continuum and outside of the laws of physics, whereas we are not. We are physical beings, constrained by the laws of physics. We have some choice, but given we are physical beings, we are bound by physical laws. While classical Christian teaching is that our spirit/soul is separate to our physical body, I don’t believe that’s possible, which I’ve discussed at length in an essay entitled “Dr Caroline Leaf, Dualism, and the Triune Being Hypothesis”, found on this blog (https://cedwardpitt.com/2014/07/25/dr-caroline-leaf-dualism-and-the-triune-being-hypothesis/)

      Finally, while I’m no theologian, I think that people often take the scripture about “as a person thinks so is he” in the wrong context, often because it’s taught the wrong way. Dr Leaf herself has used this scripture to promote the idea that what you think determines the person you are, and again, the notion seems to fit nicely with the concept of dualism that we intuitively accept. However, the scripture (Proverbs 23:7) is not referring to thought or speaking generally, but further describing the character traits of “the ruler” described in verse 1. As per the Bible Hub ‘Pulpit’ commentary, “The verb here used is (shaar), ‘to estimate, ….to calculate,’ and the clause is best rendered, ‘For as one that calculates with himself, so is he’. The meaning is that this niggardly host watches every morsel which his guest eats, and grudges what he appears to offer so liberally.” (http://biblehub.com/commentaries/pulpit/proverbs/23.htm)

      So I believe that we are created in God’s image, with choices, but those choices are constrained by genetics, priming and learning. I am not aware of any scriptural evidence that suggests that it can’t be so.

      As I have stated, I’m not a theologian, and I’m more than willing to review any evidence that contradicts me. And I’m more than happy to discuss this further if you still disagree with what I’ve said. But I certainly appreciate your thoughtful consideration of my blog and for taking the time to pose a sagacious question.

  2. Pingback: Dr Caroline Leaf and the cart before the horse, take two | Dr C. Edward Pitt

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