Field of Science

There's no such thing as a gene for religion

A new paper by Robert Rowthorn, an economics professor at Cambridge University, has been in the news recently. I'm a bit behind the curve on this one, and in fact today's post is more by way of a preamble. I'll give you the low-down on the paper itself in the next post (probably on Thursday).

And if you can't wait till then, head on over to Gene Expression, where Razib has covered it and made pretty much all the points I was going to make, although more solidly and in much more detail! Damn you gotta move fast in the internet age! In my defence, I've been like, buying a new car and stuff. Priorities, priorities...

But first I want to tell you about something that's critically important to understanding evolutionary psychology, and that's the tortuous link between genes and behaviour.

Most people are familiar with the fundamentals of genetics. You have a gene, and that generates a trait. The classic example of this is the pea experiment by Gregor Johann Mendel. The gene for height occurs in two versions, and the pea plant will either be short or tall depending on which version it gets.

You won't be surprised to hear that it's rarely as simple as this (in fact, the father of statistics, RA Fisher, accused Mendel, the father of genetics, of fudging his data - because they were too clean!).

One complicating factor is that gene expression is responds to your environment. Take a Himalyan bunny and raise it in a cool environment, and it will have black ears, nose and feet. Raise its identical twin in a warm environment, and it will be all white. Same genotype, different phenotype. OK that's a simple example, but there are plenty more.

However, these environment effects just scratch the surface of the true complexity, and I'm going to take you just a short way on this extraordinary journey. If you want to go further, take a look at the fabulous article in the New Scientist, written by Ed Yong (of Not Exactly Rocket Science). But be prepared to have everything you thought you know about genes and psychology overturned!

Ed's article deals with a gene which is a codes for an enzyme: mono-amine oxidase (MAO). When it works, MAO breaks down a certain neurotransmitters, like serotonin, dopamine and noradrenaline. When it doesn't, these neurotransmitters build up. That's it.

Like all genes, it doesn't have any grand designs, or plans. But variants of MAO do affect personality.

For example, one common, low activity version (MAOL), was found to be linked to aggression and gang membership in some boys. Yet the same gene was also linked to depression in pregnant women - a very different psychological 'effect'. Another study found that MAOL was only linked to antisocial behaviour in boys who had an abusive childhood. The high activity version, MAOH, was linked to fraud, but only in people who associated with other delinquents.

In other words, this gene did not cause aggression. The effect it had on behaviour depended on the environment.

So the environment affects the link between genes and personality. But in fact it's even more complicated than that.

Take that study on pregnant women, which found they were more likely to become depressed if they had the MAOL gene. Well, that's not the whole story. It turns out that they were only more likely to become depressered if they were also carriers of another gene (COMT).

 It's not, then, just the external environment that messes around with the psychological trait produced by a particular gene. The genetic environment also effects an individual gene.

So the effect of a gene will vary depending on what other genes it has pitched up with in the particular individual's genome. The trait a gene is linked to will change depending on what other genes you have.

What all this means is that it's fearsomely difficult to link genes to personality. So difficult, in fact, that no-one's done it yet. Neurocritic reviews the latest in a series of failures in the attempt to find a link.

It should be said that it's not just psychology that has this problem. Over the summer I went to a lecture where the the leading lights in the genetic study of adult-onset (type 2) diabetes summed up the state of play. Their findings: well, they haven't really found anything yet.

The problem is that diabetes is a very complicated disease, with a huge number of genes involved, all of which interact in complicated ways with each other and with the wider environment. There is no 'gene for adult-onset diabetes'. What there are are genes that, in the presence of certain other genes, and in the right environmental context, seem to increase your risk for type-2 diabetes.

So what does this mean for all those twin studies that regularly show a genetic link to religion?

Well, you have to remember that they are looking at closely-related individuals. These individuals share a lot of genes. So, what these studies show is that, in a particular cultural setting (say, Minnesota), a particular combination of genes can affect your religious tendencies.

Take any one of their individual genes, and put it in a different genetic or cultural environment, and it could have a different effect.

And the cultural environment is particularly important for religion, because religion is a culture and not not a personality trait. In fact, the types of personalities attracted to religion are different even in the USA and Europe - which are about as similar as any two cultures you could find!

So if you can't even link individual genes to personalities, how can you possibly link them to religion?

OK, in conclusion. I'm not saying that there is no link between genetics and religion. Clearly there is.

But what I am saying is that there is no single gene (or genes) that codes for religion: there are too many intervening steps (other genes, environmental effects on gene expression, and cultural differences in what it means to be religious) to make that simplistic link.

It seems like a trivial distinction, but it's critically important to understanding the relationship between evolution and religion. Because evolution acts on individual genes, and there is no such thing as a gene for religion.

Creative Commons License This article by Tom Rees was first published on Epiphenom. It is licensed under Creative Commons.


  1. Another reason to doubt the existence of a gene for religion is that the existence of religion itself is not well-documented. Let me explain.

    Assuming that religion is a personality trait, we ask people about the intensity and dimensions of their religiosity. But their answers cannot be be trusted, because how they answer such questions is dictated by the terms of their membership. "I am sure that Jesus is Lord," for example, is what you're supposed to say if you're in certain congregations. We have no reason to believe that people are telling us what they believe rather than what they reckon they're supposed to say. And this applies to pretty much any question you can ask anyone about someone's religion.

    We know that religious institutions exist. But we don't know that personal religious inclinations exist, because there is no way to test for them. I suspect that no one is actually religious. If this is true, then searching for a religiosity gene is a serious waste of time.

  2. It has been shown in studies that Americans fib a lot about how religious they are. They report going to church over twice as much as they actually do. This is for the reason you say-- they imagine how religious they are SUPPOSED to be, an ideal, and report that.

  3. "Yet the same gene was also linked to depression in pregnant women ..."

    Forgive me me, here you really mean 'the same allele'.

  4. The evidence for anything that could, however remotely, be called a religion “gene” is sketchy at best. To me, the more interesting (and consequential) questions are those that help identify and understand the genetic, physiological, and cultural factors that, for instance, enable the extreme compartmentalization of thinking in so many religious believers. A specific example would be someone that dismisses the mountains of evidence for phenomena like evolution by natural selection or climate change as being preposterous, while simultaneously finding the 2000+ year old miracle stories of the Christian bible as being utterly credible and reliable. To me, that is the interesting question, for despite being raised as a conservative, American, biblical literalist, it was ultimately my inability to compartmentalize my thinking which led me to reject all supernatural claims and come out as an atheist.

  5. Bjorn, I was hoping a proper geneticist would drop by :) yes, allele, dammit, allele.

    I dunno though, I'll probably use gene as a stand-in for allele in my next post, because most people understand 'gene' to mean allele. (Not me, of course, oh no. I'd never make that mistake).

  6. Romantic rationalist: I think the thing is that most people can convince themselves of all sorts of crazy things if there is an ulterior motive. For a little of people, questioning these ideas would mean risking everything else they hold dear. So they try not to think too hard about it.

    So it's not the capacity for compartmentalisation that's different, it's the willingness to risk a different approach to life (the personality factor called 'openness to experience').

  7. Thanks for the feedback Tom. I am a big fan of the “Five Factor” (or OCEAN) model and it played a crucial part in my undergrad thesis. However, I never thought of it in connection with the “compartmentalized thinking” problem until you mentioned it. This is only speculation on my part, but I would not be at all surprised, should someone actually do the research, to find that a lack of compartmentalization in an individual’s thinking would correlate strongly with high scores in the area of “Conscientiousness” and “Openness to Experience.” As you noted, a willingness to consider alternatives (“Openness”) is an important contributor to a lack of compartmentalization in one’s thinking. I would add though, that “conscientiousness” is what compels us to have our “ducks in a row,” to make doubly certain we have dotted our “i”s and crossed our “t”s, and to identify the gaps, holes, and inconsistencies in our thinking before someone else does. In conversations I frequently describe my own attitude in this regard by saying that I have a strong aversion to being caught with my “intellectual pants down.”

    Carl Sagan, in “The Burden of Skepticism” (Skeptical Inquirer, Volume 12.1, Fall 1987), eloquently (as he so often was in so many different subjects) encapsulated that combination of “Openness” and “Conscientiousness.” He observed that, “It seems to me what is called for is an exquisite balance between two conflicting needs: the most skeptical scrutiny of all hypotheses that are served up to us and at the same time a great openness to new ideas.” Is there a particular way that an individual’s brain is wired that contributes to maintaining that balance? What is the nature/nurture split in this case?

    Those of us that work for a world not dominated by credulous superstition would do well to find out if such a utopia is even possible. Blithely assuming that it is possible in this case is just as foolish as assuming that everyone could master linear algebra without asking what kind of gene-based predispositions, cultural and/or environmental encouragements, and teaching/learning strategies are needed to accomplish such a goal. I was able to tailor my undergrad degree to my interests in science communication and the public understanding of science. In all my research and reading of scientists that are actively engaged in such activities (many of whom acknowledge their debt to Sagan for making it professionally acceptable to do so) those scientists always seem to assume that winning over enough people to make a difference is possible. We already know, despite the re-normalization of IQ scores every 15-20 years, that half of humanity will fall in the lower half of the distribution of IQ scores. In light of the preceding, we can ill-afford to simply assume that some arbitrary number of our fellow human beings can be “brought up to speed.”


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