Is there a gene for loving Call of Duty?

Genes are brilliant; and yet the way they are depicted may seem to oversimplify some really complex issues.

If you watched BBC’s Horizon last week, entitled “Are you good or evil” you would have been entertained with the idea that scientists have uncovered the genetic basis of being evil. The “warrior gene” as it has been dubbed is thought to induce aggressive behaviour after provocation. In the documentary they showed a case where a man murdered his wife, but avoided a conviction for first degree murder, because scientists measured the expression of the “warrior gene” which convinced the jury that an underlying genetic trait was to blame for his actions………….I know.

If you also picked up the Metro on the 6th September (every Londoner does), you would have caught the following headline:  “Lazy people are missing athletic gene according to new study”. This gene called the “exercise” gene is believed to be deficient in couch-potatoes. The research was actually carried out in mice and the scientists demonstrated by deleting the “exercise” gene, that these mice were less active compared to their wild-type (normal – undeleted) counterparts. The gene actually encodes for an enzyme called AMP-activated protein kinase and it is a fundamental enzyme involved in metabolism, homeostasis and with glucose uptake in muscle tissues as a result of muscular contraction. Whilst it is an interesting find to demonstrate the physiological impact in mice, it might be stretching it slightly to say that it is “the” exercise gene.

Of course, our love for genes doesn’t end there, one post in a lifestyle feature describes – the “happy” gene. You guessed it, it is the gene that determines whether or not you have a bounce in your walk and see the glass as half full rather than half empty. I relish the fact that its called the “happy” gene because scientists actually called the gene 5-HTTLPR. This gene encodes for a serotonin transporter, which is a neurotransmitter (a brain chemical) that has been shown to influence mood and happiness. So albeit slightly indirectly 5-HTTLPR is believed to play a role, by affecting the transport of serotonin. One of the comments on this article is slightly amusing but also raises an important question.

tspears0901 says ” I dont care which ” gene ” anyone has, if life is tough, it makes you depressed, end of.”

“The relationship is rarely one to one.”

You see after reading these articles, I feel slightly sorry for genes. It is almost as if every single gene must have a really important purpose. The fact of the matter is, one gene does not control complex outcomes like being evil, lazy or happy. The relationship is rarely one gene to one outcome and thats without weighing in the other important factors such as nurture. So how do you even begin to unravel the importance of multiple genes at the same time and see if it can lead to complex issue? One method is by conducting gene expression profiling experiments. So taking our case of understanding the genetic basis of being “evil” you would take a group of psychotic people and then sample lots and lots of genes with the hope that you’ll identify a group of genes that you think might be important in psychosis, because it is either up or down regulated (expressed highly or less). You’ll then compare those same genes against a group of people that are not psychotic to truly identify if these genes are important, this is called your control sample. The output of such an experiment will form a genetic “profile” which, is more reliable as a measurement because you’re not just measuring one gene; it also provides a sort of genetic signature or fingerprint for that particular physical state, in this case, psychosis.

Another important aspect to consider is the functional relationships between genes. In an article published in Nature, Dr. Heather J Cordell discusses how gene-gene interactions are important in understanding human disease (link provided at the end). She states, “If a genetic factor functions primarily through a complex mechanism that involves, multiple other genes and, possibly, environmental factors, the effect might be missed if [one] gene is examined in isolation…” The crucial point here is that analysis of a gene in isolation is probably giving you an incomplete picture. Dr. Cordell then continues to describe some of the mathematical models that are used to determine working relationships between genes and this is because more often than not, it is many genes working together that leads to outcome – not just one.

“Take the word “competitive” and imagine that it is a gene.”

Some genes at this moment in time simply have no purpose, we haven’t figured out what every single gene does and it is one of the reasons why we have lots of genome projects currently engaged. One example is the “The 1000 Genomes Project” which is sequencing the DNA from a large group of people from different ethnic backgrounds. This experiment aims to identify our genetic differences and determine if such differences give rise to specific disease states. This is because for a specific gene, there can be variations in the underlying DNA sequence in specific groups (such as ethnicity) of people and as a result the functional consequences might be differ too. One way to think of it, is to consider a thesaurus. Take the word “competitive” and imagine that it is a gene. If you look up the word in a thesaurus you’ll get the following words, “ambitious”, “aggressive” and “keen”. You could in a sentence replace the word “competitive” with any of the three that I have mentioned, but it wouldn’t really give you the same meaning.

My friend Sunniyat, he is so competitive. vs. My friend Sunniyat he is so aggressive. 

Genes are similar. There are slight variations of the same gene that can have different functional consequences. Its called a genetic polymorphism. So take the “happy” gene for example, it actually may not be the secret to happiness for all of us because of our individual genetic interpretations of a single gene.

“DNA doesn’t all code for genes”

Genes are not the only functional aspect of our DNA. It may seem a little strange, but DNA doesn’t all code for genes. This is a little difficult to explain, so forgive me if this example fails to work. Imagine opening up a story book (yes another literary based analogy) and you start reading it, but it looks like this :


Imagine each word that you see in that quote is a gene, something that has a meaning and function. Our DNA is also like the above, full of lots of code that we don’t quite understand yet. The ENCODE genome project is attempting to characterise what all the code in between the genes actually do. This is called “non-coding DNA” because these sequences don’t code for genes, but just because they don’t encode for genes and they harbour an apparent lack of function, doesn’t make these sequences less important. In actual fact over 90% of our DNA is non-coding and to assume that 90% of our DNA has no functional consequence would be wrong.

“The thing about scientific research is that it is a field that builds upon current knowledge”

I don’t think scientists or science journalists are to blame here. The thing about scientific research is that it is a field that builds upon current knowledge. Hence incremental progress is reported in the papers usually with an exciting sweeping headline (ahem…) So the next time you come across an article where it describes a single gene, and how novel research has correlated it to single outcome, whether that be a disease state, behavioural outcome or physical characteristic just remember that its probably a little more complicated than that. And no, sadly there isn’t one gene for loving Call of Duty, but there might be a few!



Evil gene:

Exercise or Lazy Gene (depending on which way you want to look at it):

Happy Gene:

Gene-gene interactions:


About sunpops

I love science so much, that I want to share it with you! I'm currently studying for a PhD in Clinical Medicine Research at Imperial College London. I graduated with a MBiochem from the University of Oxford in 2009.


  1. Nice article Sunniyat. What a shame more financial analysts have not appreciated what this article says. Maybe then we wouldn’t have had so many up and coming biotech firms being valued so ridiculously high, making biotech executives rich without having delivered anything. A bird in the hand is worth two in the bush. Likewise, a drug candidate that has passed through a phase III efficacy trial is worth a lot more than a new gene being discovered (even if it’s patented).

    By the way, the thing about scientific research, is that it does not always build upon current knowledge. Have a look at Thomas Kuhn’s account of the Copernican Revolution.

  2. Pingback: Your Environment: Friend or Foe? « minimolecule

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