While I myself am very level-headed, I know many people that can have a very quick temper, such as my sisters. Both can get very angry extremely quickly. I began to think, did they inherit something that I did not from my parents? Is there a reason that they get angrier more often and faster than me, or is it just by chance? In class we talked about how your genetics could make you predisposed to become obese more than others, so I thought maybe the same could be true regarding anger. I set out to find an answer.

To use the scientific method to figure this out, I first have to set up a null and alternative hypothesis. My null would be that anger is not inherited and genetics has no effect on anger. My alternative would be that your genetics could make you predisposed to get angrier faster than others.

The first study I looked at was conducted by Dr. Redford Williams, who is director of the Behavioral Medicine Research Center at Duke. The article explained that Williams had found a small molecular variation of the serotonin transporter gene, and that copies with the long allele version of the gene had higher blood pressure and heart rates in response to stress, which are classic indicators of anger. However, I myself was a little skeptical at the claim ABC had made that this transporter gene was some type of “anger gene”. The study was done on predominately white males, which only gives a result on part of the population. If the study had been done on males and females of all races, the results could have been very different. A way to improve his study would be to randomize the population, so each person would have an equal chance of being chosen for the study.

It turns out I was not the only skeptical one of the article referring to Dr. Redford William’s study, as the next source I found was refuting it completely. Other research groups reached conclusions that contradicted William’s conclusion, and even more groups found correlations between the same gene and the tendency to become depressed, get schizophrenia, become suicidal, and more.  This led me to believe that the first source that I looked at could not be trusted. However, I wasn’t able to rule out the entire idea anger could be genetic, as the new source indicated that OTHER genes had been correlated to anger. It explained that another study had found that the enzyme COMT could influence aggression. Those that were heterozygous for the L and H allele of the gene had the lowest level of anger-related traits, while those homozygous for either had higher levels. This set me looking for other studies regarding a bad temper and genetics.

The next source found worked off the idea of aggression, which has been shown in the past to be genetic. Having a bad temper and aggression work hand in hand, but you can feel aggression and not act on it. The study, done by Thomas Denson, Carol Dobson-Sone and 3 other colleagues found that those predisposed toward aggression cannot successfully control their anger. They explained that aggression is evolutionary as those who were more aggressive in the hunter-gatherer society survived and passed down their genes. The gene correlated with aggression is the MAOA gene (helps regulate emotions), which can be high or low functioning. Two separate labs found that those with the low functioning gene were more aggressive when provoked. Also, 38 men’s brains were scanned and those with the low functioning version of the gene showed hyperactivity in the part of the brain controlling emotions, meaning they had to try harder to control their anger compared to the others. This study was the only experimental study, as they purposely made some people angry.

One more study showed that the gene DARPP-32 affects dopamine, which is linked to anger and aggression. There are 3 different versions of the gene, and those with the TT or TC versions of the gene were much more angry than those with the CC genotype. The researchers determined this by having 800 people fill out a questionnaire regarding on how they handle their anger and then had each person take a DNA test to see which version of the gene they had. Those with the TT and TC version also had less grey matter in the amygdala, which helps keep emotions in check. While this study could have skewed results because of the self-reporting, the sample size is decently large and has a mechanism for which this could work, making it a study I trust.

All the studies above talk about different genes, making the mechanism for in which anger could be genetic a little confusing. But they all are connected to emotions, making a clear case that anger is genetic to some extent. This allows us to refute our null, and tentatively accept our alternative (we’re not really sure how yet). It seems that those that are unfortunate enough to get a bad combination of all these genes are most likely more predisposed than others to be a hot head. Let’s hope you got a good combination of the genes, or you may have to work a bit harder to keep your cool!