What makes some people introverts and others extroverts?

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.

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.

family in home

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.

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.

Environmental factors

The family is essential to 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.

Middle-aged Asian Wife encourages cheerful husband to work.

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.


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