Why are Some People Extroverts and Others Introverts?

Why do some people seem to enjoy social contact more than others? Does genetics play a role? And, is it better to be an introvert or an extrovert? Find out in the following article.

Written and verified by the psychologist José Padilla.

Last update: 16 May, 2023

Some people are extroverts and others are introverts. But, what factors lie behind these two personality types? And, is there a reason that explains the differences between them?

Extroversion and introversion are both subject to the interaction of different components. For example, genetics and neurobiology greatly influence behavior, as do environment and culture. We’re going to explore how each of these variables makes some people sociable and others less so.

Extroversion and introversion

Both of these terms refer to dimensions of personality that describe and help in the understanding of how individuals relate to themselves, the world, and others.

According to the International Encyclopedia of the Social and Behavioral Sciences, extroversion encompasses traits such as sociability, assertiveness, positive emotions, and impulsivity. Extroverts are extremely active and friendly and enjoy being with others.

On the other hand, introverts are reserved, quiet, and calm. They tend to have few friends and enjoy quality time alone.

However, not all of us are extroverts or introverts. In fact, some people are located in the middle of the spectrum. They’re known as ambiverts. They express traits of both personalities. For instance, they might like having company and socializing but also enjoy solitude. 

Why are some people extroverts?

Extroversion is the result of the interaction of certain biological, environmental, and cultural factors. We can only understand its complexity by analyzing the integration of its different components. Indeed, there’s no single cause that explains why some people are extroverts.

Biological factors

Neurobiology and genetics are linked with extraversion. But, they don’t dictate that an individual is an extrovert, they simply predispose them to this personality trait. It means that extroversion is constituted by the interaction between biology and the environment.

Genetics are linked to personality. Moreover, they’re an important factor in its development. An article published in Translational Psychiatry claims that the big five personality traits, of which extroversion is one, are between 40 and 60 percent heritable. Although this is a large percentage, it’s not entirely decisive.

Research reviewed by Scientific Reports on the link between dopamine genes and extroversion found that a higher rate of dopaminergic genes is linked to sociability. These results indicate that a highly functional dopamine system is associated with behavioral traits of the extrovert personality.

The release of dopamine also increases exploration and the search for new experiences. This is mentioned in a study published in Frontiers in Human Neuroscience. It claims that extroverts exhibit this kind of behavior. Indeed, they’re often characterized by being adventurous.

In addition to genetics and neurochemistry, brain structures have a crucial impact on extroversion. In 2015, researchers Lei, Yang, and Wu, from Southwest University in Chongqing (China), studied personality from a neurobiological perspective.

According to these authors, extroversion is related to the activation of various brain regions. For instance, the anterior cingulate cortex, the dorsolateral prefrontal cortex, the median temporal gyrus, and the amygdala.

Environmental factors

Personality depends on biology and the environment. Extroversion is influenced by culture, family, and individual and social experiences. All of these factors shape the cognitive, behavioral, and emotional patterns of this way of being.

At present, culture, especially the Western one, distinguished by individualistic and business values, tends to favor extraversion over introversion. In her book, Quiet: The Power of Introverts in a World That Can’t Stop Talking, Susan Cain claims that it’s hardly surprising that the development of this personality is seen as more desirable.

Alongside culture, the family also exercises its role. For example, children who are raised by extroverted parents tend to be like them. This is because they learn by observation and imitation and behave like their attachment figures.

Similarly, social experiences affect personality shaping. So, if an individual is constantly exposed to interaction with others and participates in social activities, it’s likely that they’ll develop extroverted traits. This is because the context favors and reinforces that kind of personality.

Why are some people introverts?

The etiology of introversion is multifactorial. Its origin is found in the interaction of different environmental, biological, and psychological components. Therefore, its causes are different for each individual, in the same way as extroverts.

Biological factors

Research published in Medical Hypotheses suggests a possible association between the ABO AB phenotype and introversion. The study indicates that the ABO B allele in the ABO AB group is the driver of introversion. However, further investigation is required to confirm this relationship.

Neurobiologically, introversion is correlated with increased blood flow in the frontal lobe and anterior thalamus, according to an article published in The American Journal of Psychiatry. In addition, increases have been observed in Broca’s area, the insular cortex, and the right temporal cortex.

A study in The Journal of Sleep Research indicates that “introverts demonstrate higher levels of basal activity within the reticular-thalamic-cortical loop, which produces greater tonic cortical arousal than in extroverts”. In other words, introverts have higher levels of arousal and alertness.

Environmental factors

The family is essential in the formation of personality. For example, if an individual grows up with parents who don’t reinforce or encourage sociability, they may not have the opportunity to strengthen their social skills. One of the consequences would be feeling uncomfortable when being with others since they don’t have enough resources to interact.

However, we must stress that the above is just an explanation, not an absolute truth. As a matter of fact, introversion may not be the result of relationship difficulties, but rather a learned pattern shaped by the presence of introverted parents.

It could even be possible that the introvert simply likes to be alone, despite possessing good social skills. Indeed, many introverts know how to make friends and keep them, but prefer to spend time alone.

Introversion can also be linked with traumatic experiences. In fact, it’s common for victims of harassment, abuse, and rape to distance themselves from others out of fear, mistrust, and self-protection. In such circumstances, introverted behavior arises as a kind of defense mechanism.

Why are some people extroverts and others introverts?

Everyone has their own story and multiple reasons for being the way they are. For this reason, it isn’t correct to generalize the contextual explanations offered here. After all, everyone has their own life trajectory. Without a doubt, this is the reason why some people are extroverts and others are introverts.

Based on the above, it could be said that people are extroverted or introverted because environmental and biological variables interact with each other in particular ways. This gives rise to a behavioral, cognitive, and emotional pattern characteristic of a specific personality style.

Finally, if you’re an introvert or an extrovert, you might want to reflect on the environmental elements that may have shaped the way you are. After all, it’s useful to “know thyself” as the Oracle of Delphi once said.