The Warrior Gene

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In sports, business or your personal life, how you respond to stress and aggression may be in your genes, or at least partly so.  Let’s take a look at a great documentary and the science behind it.

Human behavior is complex and influenced by our genes, our environment, and our circumstances. One of the most provocative and often controversial of genetic variants has been dubbed the “Warrior Gene.”

Studies have linked the “Warrior Gene” to increased risk-taking and to retaliatory behavior. Men with the “Warrior Gene” are not necessarily more aggressive, but they are more likely to respond aggressively to perceived conflict.

On December 14, 2010, National Geographic Channel’s Explorer: “Born to Rage?” documentary investigated the discovery behind a single “warrior gene” directly associated with violent behavior.

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With bullying and violent crime making headlines, this controversial finding stirs up the nature-versus-nurture debate. Now, former Grammy-winning rocker, author and radio/television broadcaster Henry Rollins goes in search of carriers from diverse, sometimes violent backgrounds who agree to be tested for the genetic mutation. Who has the warrior gene? And are all violent people carriers? The results turn assumptions upside down.

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A rock band front man. A bullet-scarred Harley rider. A former gang member from East L.A. Even a Buddhist monk with a far-from-peaceful past. Which one carries the gene associated with violence? An extraordinary discovery suggests that some men are born with impulsive, aggressive behavior … but it’s not always who you think.

It’s a hotly debated topic: nature versus nurture. Many experts believe our upbringing and environment are the primary influences on our behavior, but how much are we predisposed by our DNA? The discovery of a single gene variation affecting only men, which appears to play a crucial role in managing anger, argues that nature may have a far bigger influence on behavior. It’s this low-functioning, shortened gene linked to violent behavior that has become known as the “warrior gene,” and one-third of the male population has it.

One of those men, who describes himself as “fairly furious all the time” and agrees to be tested for the gene with a simple cheek swab, is Henry Rollins — a former poster boy of youthful rebellion and the American punk scene.  Some of his tattoos are too provocative and socially offensive to show. 

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In this special Explorer episode, he dives into his own history of rage and searches out others with aggressive behavior from a range of different backgrounds. “If you can think of a stove, and the pilot light is always on, always ready to light all four burners, that is me, all the time,” he says. “I’m always ready to go there.”

Follow Rollins as he meets with former foot soldiers in one of the most violent street gangs in East Los Angeles; fighters in the ultraviolent sport of mixed martial arts, and Harley Davidson bikers. He’ll also talk to a Navy SEAL veteran and Buddhist monks whose lives weren’t always so tranquil.

After learning more about the warrior gene, many of the men believe they have it, which could offer an explanation of their past behavior. Their sentiment mimics Rollins as he says, “If I find out that I have the warrior gene, that would be interesting. If I find out I don’t, I must say, I would feel a bit of disappointment.” As the anticipation builds, be there when they receive the surprising outcome of the test.

Explorer VII: Inside the Warrior Gene NGCUS Episode Code: 4833

Then, Explorer takes a look at the original study — on one family with generations of men displaying patterns of extreme physical aggression — that led Dutch geneticist Dr. Han Brunner to the revolutionary discovery of this rare genetic dysfunction. We’ll also take a look at new revelations that warrior gene carriers are significantly more likely to punish when provoked. In one study attempting to demonstrate this, subjects are given permission to administer punishment to their partner (who was secretly instructed to make a nuisance of himself), with unexpected results.

For any man questioning his inner warrior, a simple cheek swab test is available at Family Tree DNA.

So wanna know who, in the documentary, had the warrior gene?  Well, hint….it wasn’t the biker…although his lady assured him he would always be her warrior.  But I’m not going to tell you who does have it.  All I’ll say is that you’ll be amazed at the outcome.  The link to watch the video is below.  Enjoy!

The Science

Let’s take a look at the actual science behind this most interesting and controversial mutation.

The Warrior Gene is a variant of the gene MAO-A on the X chromosome and is one of many genes that play a part in our behavioral responses. The “Warrior Gene” variant reduces function in the MAOA gene. Because men have one copy of the X-chromosome, a variant that reduces the function of this gene has more of an influence on them. Women, having two X-chromosomes, are more likely to have at least one normally functioning gene copy, and scientists have not studied variants in women as extensively.

Recent studies have linked the Warrior Gene to increased risk-taking and aggressive behavior. Whether in sports, business, or other activities, scientists found that individuals with the Warrior Gene variant were more likely to be combative than those with the normal MAO-A gene. However, human behavior is complex and influenced by many factors, including genetics and our environment. Individuals with the Warrior Gene are not necessarily more aggressive, but according to scientific studies, are more likely to be aggressive than those without the Warrior Gene variant.

This test is available for both men and women, however, there is limited research about the Warrior Gene variant amongst females. Additional details about the Warrior Gene genetic variant of MAO-A can be found in the paper titled “A functional polymorphism in the monoamine oxidase A gene promoter” by Sabol et al, 1998.

When testing for the Warrior Gene, we are looking for an absence of MAOA (monoamine oxidase A) on the X chromosomes. Based on how many times we see the repeat of a certain pattern on the X or Xs we can tell if the MAOA is present or absent (depleted). Three repeats of the pattern indicates that the X chromosome is deficient of MAOA and therefore you have the Warrior Gene. If we see 3.5, 4 or 5 repeats of the pattern, MAOA is present and this is a normal variant of the gene on your X chromosome.

warrior 6However, women have 2 X chromosomes where men have 1 X and 1 Y. As mentioned above, the gene is carried on the X chromosome, so women can either have it 1) not at all, 2) on only 1 X (therefore making them a carrier), or 3) on both Xs (exhibiting the trait).

Looking at results, with one X-chromosome, men with the “Warrior Gene” will show a value of 3. Other men will have normal variants: 3.5, 4, 4.5 or 5. With two X-chromosomes, women will have two results. For example, a woman might have 3 and 3, 3 and 5, or 4.5 and 5.

This first example is of a female with one copy of the normal variant and one copy of the Warrior Gene indicated by a value of 3.

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In the second example, shown below, this female has the Warrior Gene trait, because she carries the Warrior Gene depletion, shown as a value of 3, on both of her chromosomes, the one contributed to her by her father and the one contributed to her by her mother.  This also tells us that her father has the Warrior Gene, since he carries only the X chromosome contributed by his mother, which he gave to his daughter.  It also tells us that her mother was either a carrier, if she had only the one copy she gave to her daughter, or had the Warrior Gene herself is she carried two copies.

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A male’s results would have only one result listed.  If he has a value of 3, he had the Warrior Gene.  Any other value is NOT indicative of the Warrior Gene.

Happiness Gene in Women

In an unexpected turn of events, in August 2012, another study in the journal Progress in Neuro-Psychopharmacology & Biological Psychiatry indicates that while this gene may express as aggression in men, it may be the happiness gene in women.  Even women with only one copy of the gene were shown to be happier than women who carry no copies. A study of 193 women and 152 men evaluated their happiness level and women who carried this mutation on one or both X chromosomes rated themselves as significantly happier than women who did not carry this trait.  There was no difference in the male participants.


Among the many advances and discoveries of modern DNA and genetics are ‘scientific’ oddities. These genetic wonders make it into popular culture and sometimes develop a life there that far outpaces their academic worth.  But they are interesting. These factoids are best used as ‘cocktail party conversation’ starters or maybe a good way to tease Uncle Leo at the family picnic. Family Tree DNA, where you can find out if you have the Warrior Gene, portrays it to their customers as just that, a novelty.



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35 thoughts on “The Warrior Gene

    • Hi Judy,

      The only known source of the Estes family is in Kent, England, near Ringwould. The Estes is the US are through one northern immigrant in Massachusetts and one southern one in Virginia, both in the 1600s. So if she is an Estes by birth, and assuming no adoptions, we’re probably distantly related.

  1. I’m just curious– Does this have anything to do with the alleles that identify the people who have the gene for “Niall of the Nine Hostages”?
    Thanks, Carolyn J Inman

  2. As a 70 year old woman, I can truly attest to a fair number of women carrying this warrior gene trait. I always referred to it as a warrior mentality. The milder form translates into bullying. Off point, but interesting, I was never bullied as a child, and not until I turned 40 (and in the workplace), and from an equal number of both genders. Thank you, Roberta, for this very thought provoking article.

  3. Roberta, do you know if the 23andMe or the FTDNA 111 tests cover this gene and if so is there an online program to plug my results into to check for it??

    Michael Gregory

  4. Roberta, do you know if the 23andMe or the FTDNA 111 tests cover this gene and if so is there an online program to plug my results into to check for it??

    • The 111 marker test tests the Y chromosome, so that has nothing to do with it. The warrior gene is on the X, so you’d need raw X data AND a way to interpret it. If that is available “on the side” so to speak, I don’t know about it. The test isn’t expensive at Family Tree DNA.

  5. Hi Roberta
    Based on your blog, I went ahead and ordered the test from Family Tree DNA. I have always believed that I inherited a happy hearted disposition from my paternal grandmother based on things I was told more than 50 years ago but without any scientific basis. I just got the results back from FTDNA and I do have one copy of the happiness gene. Maybe that is half a scientific reason to believe that it is heredity that causes me to be happy unless there is something horribly wrong to cause me to be unhappy. Will there ever be a way to tell from which grandmother, if either, I inherited the happiness gene?

      • I thought of trying to have my nephew dig up their graves but I was discouraged by the fact that it is illegal and we might get caught. Then when I read something you wrote that indicated that digging up graves probably wouldn’t work well anyway for DNA purposes, I totally gave up on the idea. Maybe the DNA science will improve in future years so I can find out before I die by just using my own DNA. Some problems don’t have a good solution.

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  9. This was the first result on my DNA test results:
    Probably one Warrior Gene and one non-Warrior Gene. Women with this combination usually have the 3 repeat MAOA Warrior Gene on one X chromosome and the 4 or 5 repeat MAOA non-Warrior Gene on the other X chromosome. The 3 repeat Warrior Gene makes people more aggressive and antisocial. If you are a man, there was a problem reading this SNP (or you are XXY).

    However, my son is the kindest person I know, who unfortunately never shuts up. Not even in the movie theater. I don’t think I passed it on to him. I hope. The alternative sounds frightening.

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  12. I have a double warrior gene as do all my 6 sisters, while my 2 girls have one warrior gene and a non-warrior gene. In my family of origin the 7 girls were hands down more aggressive than the 3 boys. What I think is that they do not know how to quantify aggression in women as they look at it through a male lens. I also know that I am more aggressive per say than my daughters. My daughters are more aggressive than my 2 sons. I think researchers should look at what female aggression looks like because I bet it looks a lot different than male aggression. In a society that teaches women to act different socially than men, and puts a lot of restraints on them of course it will look different in females.

  13. I am female and have both copies of the Mao gene and what I think that a lot of these articles miss out is the influence of hormones. When I am estrogen dominant, I am definitely more aggressive as estrogen slows the gene down even further I believe. The rest of the time I am generally happy which until I figured out I had this gene, left me struggling with extreme mood swings which did not seem to have a direct cause. I am also led to believe that progesterone and testosterone speeds the gene up. If this is true looking at the gene in isolation with no info regarding levels of hormones is not going to very useful. This explains why it affects some people and not others.

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  15. Hi Roberta! I have a question, I got my answer of the Worrior gene, from Ftdna a few months ago. My result;” I do not have the Worrior gene” . I had 4 Repeats Normal variant.
    But my daughter, who I also tested, has the Worrior gene 3 and 4 Repeats
    One copy each of the Warrior and Normal Variants.
    My question is, am I a carrier, with this “4 repeats normal gene” , OR can a woman, inherit the gene from only one parent? I understand that father, must have had the worrior gene. OR can a woman inherit from only one parent, her father? Lika a male would?

  16. I seem to be a bit confused about this gene. I have 2 copies of it but it’s of the t variant – isn’t that non aggressive? I thought C made it the warrior gene

  17. I’m kinda concerned people are so quickly to “brand” this gene without fully understanding it first. This “warrior” brand comes with it all sorts of connotations like glory, discipline, strength, honor. Being tied to aggression, it could just as well be easily called the “Psycho Killer” gene. Or even as the article says with woman the gene elicits happiness traits and hence maybe you can also brand it the “fuzzy cuddle” gene. I think some further research and more in depth understanding of how such genes interact with other genes or brain chemistry in different people and in environmental upbringing before slapping some general misleading label on it.

    • I have tested positive for the Warrior Gene some years back with FTDNA. Had one fight at 8 years old and was beaten up by a 12 year old … the only one I have lost. My little brother had picked a fight with his 10 year old brother and I had taken over, as it was my duty to look after my little brother (5 years old). My wife says my medium grey eyes go charcoal when I get mad. In other words the other guy knows about it before I do. I have also been a Prison Officer in three different Prisons … Maximum, Medium and Minimum. The first one of about 350 inmates they nicknamed me …. Smiley. Three years later I came to South Australia from New Zealand and discovered some of them knew me from the first Prison and so I was stuck with the nickname. Ten years in the RNZN (Navy) (1960-70) I had discovered that I sleep with my eyes open …. actually one of my daughters was talking to me after I left the Navy, working nights as a Mobile Security Officer, and I was asleep during the day. She thought I was awake as my eyes were open. My step father asked me before I left for a year in the Far East in 1962, how come he could never get into my bedroom at 0400 when he came to wake me to go fishing. I told him that he cut the light out from the street lights shining through the strip windows by the front door, and down the hallway. Whilst in the Far East one of the guys took me around all the Indian warships trying to get them to fight me. And to think he was a champion southpaw boxer from Southland in the South Island. Either way they did not take him up on the offer. We had actually come close to blows the year before whilst on Royalist when he and his mate decided to have fun and use black boot polish on me …. and I decided no and pulled my knife (pusser’s dirk) out and was about to take them out; one look at me and they decided no they would not do that today!

      So there is really nothing about glory, strength, or honour; although there may very well be discipline in refusing to fight. I used to “play” whilst learning Kendo back in 1980s and after having fought a number of younger guys in their teens (25 February 1944) I over heard them talking in the change rooms, how vicious I was to fight. I grinned to myself as I consider it part of teaching my opponent. I remember back in 1982 trying my hand at Karate and I was put in with a young lady in her teens, as my partner, to fight. So we fought and I was teaching her that I am the bad guy and she must put more emphasis into fighting me …. I may have appeared tough but the idea was for her to realise she must keep her cool, but also think her way through the game. I hope I was successful …

      Should have seen the story I wrote first before it was deleted by this stupid Lap Top I have bought to take the place of my fried desktop computer, that the local Computer Shop killed!

        • Never beat up on her, just made her work harder to beat me; the next week I had to fight a Black belt guy going for his 1st Dan and I was not permitted to hit him with my fists, but had to allow him to kick me, as did all the others who fought him; he discovered my left knee that had been damaged some eight years before, working Special gang on the South Australian railway, and proceeded to kick that knee. Went to the hospital later on and they stated it was extensively damaged, three months later and I returned to training, only to find I still could not work with the exercises. Another ten years later I found I could finally run again. Consider this, if I had not been that girl’s partner she would have had to fight a guy of her own age; her choice then would have been he would have considered her his equal and hammered her, or not done anything and she would never have learnt anything.

          Try another senario, my eldest daughter went to High school when we arrived in Australia, in January 1979, and a week later she was beaten up, knocked unconscious by all her female classmates, because she “knew too much” . Spent the day in Sickbay and they finally rang to ask me to pick her up. When we got home I asked her why she did not retaliate as she knew Karate … yes I knew it before that first time, as a Prison Officer in Maximum Security … and she replied she was not going to lower herself down to their level. At the end of the year she came home smiling and said “she won”. She had got all As, plus one B for music and one C for physical education. Oh …. previously to this time she had taught herself to play the piano, so perhaps the music could have been higher grade too. Either way the other girls had left her alone after that first belting and must have accepted that she was going to do her schoolwork regardless of their mentality.

  18. In the sample results charts for female, they both say the same thing! So how could one be the Warrior and the other not?

  19. Of course it’s less studied in females. Most things are. It’s why I went most of my life not knowing I was autistic. The traits I was exhibiting sort of matched up with male autism but not enough that it couldn’t be explained away with other things. It wasn’t until I was much older and saw a new study on autism in females that I was shocked to realize how closely it matched up with my symptoms and experiences. Knowing that information sooner could have saved me from decades of needless suffering.

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