Siddhartha Mukherjee is a brilliant cancer doctor and author based in New York. The prevalence of schizophrenia in his family inspired him to research and write, The Gene, an intimate history[1]. It is a wonderful book, explaining the history, and the mystery, of genetics.

When we talk about mental health it is important to get the science right. The Gene taught me several things about this, here are some useful highlights.


First, is there a gene for mental illness?

Yes and no; some illnesses do have a genetic component. But no single gene codes for mental illness. Most disorders that are influenced by genes are polygenic – the result of a multiple genes working together. Schizophrenia, for example, is one of these. In mental health, we need to talk about combinations of genes, not one gene acting on its own.


Second, if I have the right combination of genes, will I inevitably get the condition?

No, genes are one of several risk factors but on their own don’t always make you ill. This is because:

  1. Some genetic combinations have poor penetrance – this means that they are not very effective at expressing themselves in your life. You may have all the right (or wrong) genes, but they may never have any effect on you.
  2. More importantly, genes are not the whole story, because some need to be switched on or off by other genes or proteins in the cell. These switches are activated by your environment. Many aspects of a person’s life can throw these switches; family, security, stress, trauma, mutation and so on – the whole gamut of human experience.

Someone once said to me, ‘My genes loaded the gun, but my boss pulled the trigger’. That sums it up quite nicely. Many genes need to be activated by other risk factors.


Thirdly, is there such thing as normal?

Eyes can be brown, blue or grey, but which colour is normal?

Silly question!

That’s why geneticists speak of variation, rather than normality. Variation is nature’s way of finding new solutions to problems, and some variations of mental states can be very useful in some circumstances.

Here’s an example. You are a leading a patrol behind enemy lines, night falls so you set up camp and post sentries. In your platoon you have two soldiers who are prone to anxiety, you have two others who could sleep peacefully through a bombing raid. Who will guard your platoon most effectively?

An anxious person may be best for the job! He/she is well adapted for risky environments. So rather than talk of ‘normal’ or ‘abnormal’ we could speak about ‘variants’ of mental health. Each variant has a useful function in different circumstances.

For sure, some mental health conditions are so disruptive that it’s hard to see the usefulness of those in any environment, but the language of variance neatly eliminates the – sometimes stigmatising – language of ‘normality’.


Finally, can genes have an influence on personality?

Yes, it turns out that they can. I liked this passage from the book.

Children with Down syndrome have an extraordinary sweetness of temperament, as if in inheriting an extra chromosome they had acquired a concomitant loss of cruelty and malice. (If there is any doubt that genotypes can influence temperament or personality, then a single encounter with a Down child can lay that idea to rest).



From a Mental Health First Aid perspective, I think we can capture all this as follows:

  • Genes influence, but do not determine our mental health and personality.
  • If someone knows of mental ill health in their family tree it can be reassuring to know that other trigger factors are needed for some genes to express themselves
  • The fact that environment does influence gene expression is a useful starting point for a discussion about how person might best look after their mental health
  • Talking about variation, instead of normality may help keep stigma at bay


[1] The Gene, an intimate history, Siddhartha Mukherjee, Vintage, ISBN 978-0-099-58457-5


Share This