Can 'warrior gene' explain violence?


The 10-year-old spun around with a Walther PKK and emptied the clip. The supervisor lay dead with a dark red splotch on his shirt. Three children slumped dead or wounded on their bus seats ....

I began this scenario in my last article with a boy who looked down a dark street and didn't want to leave the bus.

In the flight-or-fight scenario, he is likely to have panicked and either frozen or taken off in a run.

In our thought experiment, I've chosen the violent response for an opener. Let's accept that sudden violent behavior is a concern to modern society and one of the emotional situations that exists in what I consider to be a driving force for a limited number of gang-bangers.

What makes those youngsters different? Does that inform us about what we can do to improve things?

Hans Brunner, a Dutch researcher, described the "warrior gene" in 1993. The originally described gene coded for an enzyme that is needed to keep neural transmission going. It was located on the "X" (male) chromosome. We humans are thrilled to find an apparent answer to complex questions. Might bad-boy behavior be defined by a specific inheritable anomaly that we could do something about?

I would like to look at the latest progress later but hope to begin with basics. Parts of DNA coils, genes, function as templates for RNA and, in turn, proteins like MAOA, a defective enzyme. In the case of my hypothetical 10-year-old, electrical connections are going wild in his brain. The number of centers involved is greater than we once thought and one nerve cell may connect with thousands of others. If this boy has the warrior gene, the conduction is impaired because the enzyme can't keep the pathways cleared.

Could we explain the boy's outburst as uncontrollable behavior, set off by a stressful event and not fully in his control?

The answer is "yes" with the caveat that it is one of multiple factors. Violence, even psychosis, has a genetic link. The good news, I believe, is that the other factors may be more amenable to change than modifying brain chemistry with another drug. The problem is large, pervasive, and it has been around as long as mankind.

A 1994 movie, "Once Were Warriors," takes us into a violent New Zealand household.

The husband is an unemployed alcoholic who wins bar fights and brutalizes his wife.

His son joins a gang. The movie flashes back to earlier Maori culture. Not long ago, the warrior played an important role in protecting his family, his tribe, and his society. (The justified role in our society is a question better left to a philosopher and a different column in the paper.)

The warrior has a tough time in "normal" social settings, if his violence switch is set to go off easily. The fact that his son joined a gang becomes easier to understand, if we recognize that an unstable home rewires our brains.

The mechanisms, including epigenetic studies are fascinating subjects for a later time. The movie demonstrates what science has struggled to explain.

We have had two decades to understand more about the warrior gene and those of us who have brains that need quick answers have been disappointed by the complexities involved. Others have enjoyed seeing new windows opened to even newer discoveries. A short list of things that we have learned includes the following:

The gene is common, but not everyone with the gene exhibits the behavior. Early childhood experiences set the stage and some incident turns on the bad-behavior switch. Prisoners who are guilty of violent crimes are more likely to have the faulty warrior gene. They are also likely to have grown up in severely dysfunctional families.

There is more than one variant of the gene and they are not all linked to the "X" chromosome. Some women also deal with antisocial behavior linked to warrior-type genes.

A study reported from Florida State University, (in "Comprehensive Psychiatry" by Kevin Beaver) indicates the warrior gene contributes to gang membership and that the carriers of the gene are four times more likely to carry deadly weapons. Like most science, the observations require duplication and they are subject to criticism.

Perhaps a third of men carry a variant of the gene. Most don't become violent.

Genetic determinism doesn't explain the phenomenon, or the reason that a 10-year-old would go Rambo in the bus.

The role of ACES, adverse childhood experiences, has become a popular subject of study.

We've learned that a specific list of bad experiences predict that children will grow up with severe behavioral problems. We may develop ways to intervene and squelch the effects of the warrior gene.

We have to be ready for disappointments and use those as stepping stones to get back on track. Perhaps, above all, we have to be careful about trying things with the assumption that we can't do harm.

Trying to help doesn't always make things better. That brings me to my next column. Might the boy be a psychopath? If so, could he have been helped by a caring environment?

There is an argument to be made that psychopathy is very different.

At age 10, the Green River Killer may have been observing behavior that he could mimic for ill purposes.

Until next time ... psychopathy-empathy-gangs.

Dr. Larry Mulkerin is a retired clinical professor. He can be reached at


Use the comment form below to begin a discussion about this content.

Sign in to comment

Click here to sign in