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Do I Have to Wear My Genes: Genetic Determinism & the Priesthood Gene

By Andrew George.

There has been some speculation in the media about the determinative effects of certain genes. The author helps us to understand the value of genetic determinism by reference to the discovery of a gene for priesthood!

One continually hears on the news that scientists have discovered the gene for a disease, or for some personality trait. Thus, for example, genes have been described for homosexuality, and for risk taking, and for breast cancer. However, too often there is little explanation of what this means, and such pronouncements are taken as signs of genetic determinism, as though the presence of the gene absolutely determines whether one is going to be homosexual, climb mountains or get a particular disease. The aim of this paper is to discuss what it means to talk about the gene for this or that, and to explore some of the consequences of the knowledge.1

I will take as my premise that there is a gene for priesthood.2 I will use this example to explore what it means to ‘have a gene for...’, and to dissect what this does and does not say about us. As it happens, I am reasonably confident that, if someone wanted to invest the time and money into the process, it would be possible to discover that there is indeed a ‘gene for priesthood’.

Why do I believe there is a gene for priesthood?

First, I should describe why I believe that there is a gene for priesthood, a belief which may infuriate some readers of this journal. It is probably not controversial to believe that priests, as a body, have particular skills, behaviours and propensities If this were not so, stereotypic caricatures of priests on TV or film would not be successful. This does not, of course, mean that every priest behaves exactly like the Vicar of Dibley, but we recognise that portrayal as being, in some way, representative (at least of a type!).

Once we accept that there are characteristics that can be used to differentiate between priests and laity, then it is reasonable to ask what causes these differences. Of course, they may be due to environment (the theological colleges, or the formative years as a curate). However, increasingly we are beginning to realise that there are few personality traits that are not influenced by genes. Indeed, genes can be discovered for risk taking, for aggression, for promiscuity. There are probably genes for wanting to pray, or helping other people, for having a theatrical desire to perform in public. If this is the case then it is almost certain that there is a gene for priesthood.

Incidentally it would be quite easy to test whether this hypothesis is correct, at relatively little cost. The classic way to do this is by twin studies. Twins share - to a large extent - the same environment. However, identical twins also share the same genes. So it should be possible to collect as many priests as possible who are twins and ask the following two questions: “Is your twin a priest?” and “Is your twin identical or non identical?” If I am right, and there is a gene for priesthood, then identical twins of priests will be more likely to be priests than non identical twins - as identical twins share the same genes (and so the same putative ‘priesthood gene’).

How could one find a gene for priesthood?

It is worth spending a little time describing how one might find out what the priesthood gene is. There are two ways. The first would be to collect as many priests as possible and take DNA samples from them. One would also take DNA samples from a similar group of people (matched for things such as sex and ethnic background), and ask if there are any differences in genes between the two populations3. One might discover a gene that is present in 45% of priests, but only 5% of the normal population. That would be a priesthood gene.

The alternative approach, which is often used to find genes for diseases, is to use family studies. To do this, one would need a number of large families which have a high incidence of becoming priests, and in which one can see that the chances of becoming a priest is inherited. One postulates that the reason why these families have a high risk of being a priest is that there is an unusual gene (we would normally think of a mutation, but that is perhaps a bit disrespectful to some of the great ecclesiastical families of this country), which puts members of that family at risk of becoming a priest. It is then possible to look at the DNA of the family and determine which bits are inherited by those that become a priest, and which are not. Again this can lead to finding a priesthood gene.

A third way to do the study, which I include for completeness, is to find an animal model for priesthood. If one could find a strain of mice that showed priestly behaviour, then by careful breeding of these mice onto ‘wild type’ (i.e. normal) mice, it is possible to find which genes cause the mice to become priests. As I am unaware of any useful animal models for priesthood, I do not think that this is a viable approach.

Already a description of these approaches to identifying the priesthood gene indicates some of the limitations of this approach. In the first case I suggested that the priesthood gene might be present in 45% of priests, and 5% of normal people. This is quite a strong genetic link, and geneticists would have no problem in using the term ‘gene for...’ to describe such an association. However, two things become clear. First, it is clear that you do not need to have the gene in order to be a priest. More than half the priests do not have the gene. Second, if you have the priesthood gene, you are not condemned to being a priest, since 5% of normal people also have the gene. Indeed if 1/10,000 people in the country are priests, then for every priest (with or without the priesthood gene) there are 500 lay people with the priesthood gene (5% of 10,000). So even if you have the priesthood gene you are not very likely to be a priest.

The second approach, using the families inflicted with a high incidence of priests, also has its disadvantages. It is a very powerful approach if the penetrance of the gene is high. Penetrance in this case refers to the probability of getting the condition if you have the gene - a penetrance of 100% means that everyone with the gene gets the condition, whereas a penetrance of 10% gives one a 1/10 chance. This approach is often useful in finding mutant genes with close to 100% penetrance in a particular family, but is not useful if the gene only predisposes to a condition.

Give me a boy until he is seven and I will give you the man

So far we have not considered the environment, and the famous Jesuit aphorism indicates that, at least for that section of the Church, the environment is an important factor in determining who becomes a priest and who does not. This is of course true. Religious education, childhood mentors, the encouragement of a parish priest are all important parts of whether an individual becomes a priest. This takes us into a Nature versus Nurture debate. Is the reason why someone is a priest because they were made that way (their genes) or because they were made into that way (environment)?

In general, Nature versus Nurture arguments miss the point. There are relatively few things that are entirely nature (eye colour might be one) and relatively few things that are totally nurture (the language we speak). Even the relatively noncontroversial examples I have given are not totally clearcut - as we age our eye colour changes, due in part to exposure to the sun. There are aspects of our language that are probably ‘hard wired’ in the brain. So we can try and have a sophisticated version of the debate, tying to work out what proportion of being a priest is due to genes and what proportion is due to environment.

Unfortunately things are not as straightforward as this. First there are the influences of other genes to consider. When we talk about the priesthood gene, we have to remember that this gene will operate within a complex series of interactions with all the other genes in the human body (around 40,000). The outcome of what a gene does depends on what other genes are in that body. It is rather like a playing card - its value depends on the other cards in your hand. The Queen of Diamonds may be a useful card to have if you also have the Ace, King, Jack and 10 of Diamonds, but rather less use if the rest of your hand is made up of clubs, hearts and spades. Someone who has the priesthood gene, who is also outgoing and confident, is perhaps more likely to become a priest than someone who has the priesthood gene, but is also shy and does not like people.

The way in which the environment interacts with the genes is also complex. You may well need the combination of nature and nurture to trigger off a vocation. Thus, a parish priest may suggest to a young person that they become a priest, and that might cause them to investigate the possibility. If the person is never approached then they might never be a priest. However, they might need the right genes in order to be responsive to that call - the same parish priest may have made the same suggestion to hundreds of other young people to no effect. It needs the right combination of nature and nurture for a priest to be made!

The other complicating factor is that different genes might be operating in different environments. To take an extreme example, the environment in Great Britain at the start of the 2lst century is very different from that of Imperial Rome in the time of Nero. The priests of Imperial Rome would be very different from those of today. Therefore the way in which the environment would interact with the genes to determine who becomes a priest will be different, and there are likely to be different priesthood genes operating.

To illustrate the complexity of the interaction between a priesthood gene, other genes in the body and the environment, consider the situation in the Church of England before 1992. At this time any individual who had the priesthood gene and also did not have a gene called SMCY would not have been able to be a priest. This is because everyone with the SMCY gene is male, and the Church of England before that date would not ordain women. This shows how complex the Nature vs. Nurture debate really should be. Was a woman before 1992 unable to be a priest because she had the ‘wrong genes’ (nature - maleness is a genetically determined condition)? However, in 1992 her genetic makeup remained the same, yet now she could be ordained. The only thing that had changed was the environment, and the result of the Church changing its rules was to break the interaction between the priesthood gene and the SMCY gene.

In summary, the effect that a gene has must be seen in light of the environment and of the other genes that are around it. This interaction is complex, and should not be thought of as ‘either nature or nurture’, but rather ‘both nature and nurture’.

Why is it interesting to know about the priesthood gene?

What does knowledge about the priesthood gene contribute? There are several possibilities. The first is that knowledge of the gene might allow those bodies charged with accepting people for training for the priesthood to more accurately identify suitable candidates. One could envisage everyone going before a selection conference could have a DNA test to see if they had the priesthood gene.

Would this be a good idea? If we take the example given earlier in which 45% of priests had the gene and 5% of laity then clearly this policy would be crazy. Assuming that the 55% of priests without the gene are good competent priests, then the Church would be missing out on a lot of talent if they rejected them on the grounds of not having that gene. There is also the risk of a group of unsuitable people being accepted for training simply because they had the gene.

However, it may be possible to improve the accuracy of the test (possibly testing for multiple genes). Alternatively it might be possible to accurately identify people who should be excluded (the philandering gene might be a case in point for parish priests). As stated in the earlier footnote, I do not want to consider the ethical issues here, important though they are. However, I would point out that because of the complex interaction of genes and the environment it will always he difficult to be precise. It is also important not to get trapped in the straitjacket of genetic determinism. If someone has particular genetic traits (for example, aggression), then they may end up picking a fight every Friday night, or they might find an alternative outlet for their aggression (kick boxing in the gym) or they might receive support and counselling that enables them to channel their aggression in a constructive manner, possibly through their work.

A second use of the genetic information would be to identify those at risk of becoming priests. At one extreme this could happen prenatally. If we take a family that had been cursed by having too many priests, it might be possible for a pregnant woman to have a genetic test to help her to decide whether to undergo a termination of the pregnancy. Alternatively, it might be possible to do preimplantation diagnosis in which eggs are fertilised in vitro, allowed to grow for a few days and then assessed for the presence of a particular gene. In such a case it would be possible to identify those oocytes at low risk of becoming a priest and choose those for implantation. Again, the crucial scientific factor in this would be the accuracy of the diagnosis. If we take the example that we have been using so far (5% of laity and 45% of priests having the gene, with 10,000 laity to every priest), around 1000 pregnancies would be terminated or oocytes not implanted in order to prevent one priest from being born.

An alternative use of this knowledge would be to try and modify the environment in light of information given by the genes. If we stick with the example of a family not wanting a priest as a son or daughter, then if they knew that a particular child had the priesthood gene then they could try and modify their environment appropriately. They may choose, for example, not to send them to a Jesuit school!

This knowledge could also allow one to plan for the future. If you know that you are likely to become a priest then you might plan your finances appropriately.

The knowledge of what the priesthood gene is would also be interesting scientifically. Genes encode for proteins that have functions in the body. So knowing what genes are found most commonly in priests would allow one to research what proteins are different, and how they affect the way the body works. This would be fascinating information. It might also allow scientists to design drugs that could mimic (or block) the way in which that protein works. So there might be a drug that could make people more (or less) priestly.


I have suggested that there is probably a gene for priesthood. However, I have also pointed out some of the limitations of this knowledge. When we talk about the ‘gene for priesthood’ it does not mean that someone with the gene is inevitably going to become a priest. That will depend on their other genes, on their environment and the way in which they as individuals respond to their genes and environment. Free choice is not lost!

Having pointed out the limitations of the genetic knowledge, and hopefully indicated the weakness of genetic determinism as a position, it is important to stress the importance of genetic knowledge. As our knowledge of the genes increases we are going to be able to predict with greater and greater accuracy the likelihood of people getting certain conditions - especially diseases. In most cases this information will not be absolute (thought sometimes it will), but we will be able to tell our risks compared to others of getting heart disease, depression, cancer or many other diseases. This will allow better prevention, diagnosis and treatment of disease. This knowledge has its costs, and we also have to consider both as society and as individuals how we wield the power that this knowledge gives us. But that is a debate for another day.

Andrew J T George is Professor of Molecular Immunology at Imperial College, London

Ministry Today

You are reading Do I Have to Wear My Genes: Genetic Determinism and the Priesthood Gene by Andrew George, part of Issue 27 of Ministry Today, published in February 2003.

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