Introduction

In Pixar’s classic Inside Out 2, a teenage girl’s emotions are portrayed as distinct characters that control Riley’s thoughts and emotions. Among them is Anger, a fiery little man living in Riley’s brain since she was born. However, the depiction of Anger begged the question: are people born with anger, or is it triggered by certain external influences?

So, why do we feel anger, and where does it come from? The answer lies in the nature vs nurture dilemma, which refers to the interplay between genetic influences and environmental influences. When discussing anger, we need to acknowledge that anger is largely influenced by temperament, or traits that shape how a person interacts with the world. Experts from Michigan State University say temperament, and deciding factor in expressing and feeling anger, can be influenced by factors as minute as sensitivity to stimuli; for instance, people more sensitive to bright light that is usually harmless to others tend to be more likely to feel stressed and angry.

This leads us to another question about the origin of the anger: Are temperaments inherent or more influenced by individual experiences?

Nature: Hereditary Factors

Studies from Medline Plus estimate that 20% to 60% of temperament is gene-determined, showing that interactions between thousands of gene variations (polymorphisms) influence each individual’s unique temperament. Though scientists haven’t yet mapped direct paths from specific genes to certain expressed characteristics, they have found several genes that play broader roles in temperament:

DRD2 and DRD4 genes relate to a desire to seek out new experiences.

KATNAL2 is associated with self-discipline and carefulness.

PCDH15 and WSCD2 genes connect to sociability.

MAOA genes are linked to introversion.

Genes such as SLC6A4, BAIAP2, and XKR6 contribute to anxiousness and depression.

Another notable gene found to have an effect on aggression, criminality, hostility, and antisocial behavior is 5-HT2A. This gene instructs the production of the 5-HT2A receptor, a serotonin signaler that influences the amount of positive emotions a person feels.

A study published in the Journal of Physiological Anthropology showed that a specific mutation of the 5-HT2A gene, named rs6311, is associated with impulsive reactions in healthy adults. Participants in the study with rs6311 rated themselves as having higher total aggression, suggesting that they have a genetic predisposition towards anger.

Nurture: Environmental Factors

However, the development and expression of anger, as well as other temperamental traits, cannot be fully explained by genetics. While genetic predispositions can influence emotional reactivity, life experiences also influence how these traits are expressed. Thus, even though personality has a general pattern of continuously maturing over a lifetime, the pace of change and the specific form it takes can vary greatly.

A study mentioned earlier in the Journal of Physiological Anthropology concludes that aggression is not only determined by genetics, but also by cultural background. This research examined two environments: the rural, traditional African society of Datoga, and one urban, industrial Russian community. The data shows highly contradicting variations in serotonin-related genes, such as 5-HTTLPR and 5HTR1A, suggesting that cultural norms around aggression play a crucial role in emotional responses.

For example, the Datoga scored the highest total aggression, as their society is more accepting of aggressive behaviors and the dynamic expression of anger to survive in the group. For these communities, aggression is a key adaptive trait to secure leadership, assert dominance, and defend resources, which even suggests an evolutionary benefit to being more aggressive within these communities. However, the Russians have a different culture that values social conformity and collaboration, leading them to have comparably lower levels of aggression.

Conclusion

The origins of emotions, including anger, have always been a popular debate topic: Is nature or nurture the deciding factor in our reactions? There isn’t a clear answer yet, as results of various studies on the topic were all highly dependent on each participant’s unique personality, cultural background, or life experiences. Recent studies continuously suggest new perspectives , as anger can also be stimulated by other emotions such as anxiety or the release of stress hormones from flight-or-fight responses.

Regardless of this, the most crucial takeaway is that we can control our anger in certain ways. Each individual has a unique temperament and sensitivities, so it’s vital to cater to individual needs. Individuals with sensitivity to sound should seek out quiet environments; individuals who are easily overwhelmed can seek out relaxing environments for themselves; individuals with high activity levels should take frequent breaks to stretch.

Ultimately, small adjustments to daily routines such as these can help us better understand our temperaments and how to work with them, reducing stress and anger day by day, no matter what the cause is.