Ask a Geneticist

by Dr. Barry Starr, Stanford University

Is the tendency for anger genetic?

-A high school student from California

Wow, this one was a toughie! What we are really talking about here is getting angry easily. Some work in behavioral genetics suggests that this trait can be inherited.

As anyone who has kids can tell you, there are some parts of personality that seem to be hard wired. Scientists who have studied this have found that one of the strongest inherited genetic traits is something they've called temperament.

Temperament is made up of three parts—emotionality, activity level and sociability. What we're interested in here is emotionality. Emotionality is how easily someone gets scared or mad in upsetting situations.

From lots of different studies, it looks like about half of our emotionality is inherited. The other half comes from where we live, how we're raised, etc. (See the twin study link below to see how these studies are done.)

But how could something like how quickly we get angry be inherited? To be inherited, genes have to be involved somehow. Genes are involved in every step of anger from what makes you mad, to getting mad, to getting over being mad.

Anger happens when something around us causes a bunch of chemicals to be released in the brain. These chemicals (called neurotransmitters) then eventually tell the body to make our hearts beat faster, increase our blood pressure, etc.

How do these chemicals work? They attach themselves to special proteins called receptors and turn them on. Once enough receptors are turned on, other proteins are turned on as well. Eventually you get something to happen like a pupil dilating or palms sweating.

One example of genes that could be involved in our anger response are the ones related to the chemicals and receptors. (There are lots of other ways too but we'll use this as an example.) Remember, these chemicals and the receptors are made from instructions found in genes.

What if some people had a version of a gene that resulted in a stronger chemical being made? Or more of the chemical being made in a certain situation? Or a receptor that needs less chemical to work? They'd all get angry more easily.

Maybe a concrete example will make this easier to understand. Let's say Bob gets mad when he tries to program his DVD player but Sam doesn't. Let's say it takes 100 of a "normal" chemical to generate an anger response.

Sam might make only 90 but Bob makes 110 in this situation. Or Bob makes 90 but they're stronger or his receptor is more sensitive so it is enough to get him mad.

Now we understand why Bob throws the instruction book across the room and Sam keeps on trying—his genes made him do it! And if Bob passes the gene onto his kids, then they may throw the instruction booklet across the room. Sam's kids may be able to handle the frustration better.

Of course, it most likely isn't that simple. There are probably hundreds of genes involved in such an important response, all affecting each other. And we need to remember that it isn't all genes—half of our emotionality comes from our environment.

Genetically, the next research step is to figure out the genes involved. While this won't be easy, research on this topic is helped by the fact that animals get angry too and have similar responses. Also, there are some mental diseases that result in getting angry quickly. Understanding these diseases at a genetic level should give us some idea of how "normal" anger happens.

Finally, with the sequencing of all of the DNA in humans, scientists can begin to look at the small changes that make us all unique. If they compare people who get angry easily and less excitable people, they may be able to pick out the changes involved.

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