Debate: “What influences personality traits the most?”

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On March 24th the Language exchange team of A.P.E INFO held a lively American-style debate, where two groups of psychology students debated on a classic controversy, which has been discussed among experts for centuries – Nature vs Nurture: What influences personality traits the most?

The debate was held by moderator Lisa Gunnarsson and consisted of two defense teams: nature group participants were Lara Lukaschewitsch and Cecilia Gremmo; nurture approach was defended by Selin Erol and Zerina Muftic.


The Nature team opened a discussion by highlighting that in the last years the discipline of behavioral genetics has successfully established causal links between genes and human behavioral traits using evidence from Twin as well as Adoption studies.

  • Twin studies support the theory that genetic factors are primarily responsible in determining personality. Studies depict correlations between twins on a range of personality traits such as empathy and hyperactivity.

Studies have shown anxiety and depression in the neuroticism domain as well as positive emotions in the extroversion domain can be explained up to 65% by personality-related genetic influences.

  • Adoption studies, which have consistently shown that adoptive children show greater resemblance to their biological parents rather than their adoptive or environmental parents, even though they have never met their biological parents.

On the other side, Nurture team stated that family theory supports their position, since if genetics had a role in formation of our personality traits, then we would have the same type of personality as our parents. 

Evidential basis can be found in Gene Theory: researchers in this study could not find whether certain genes affect certain personality traits.


Nature defenders explained their side of argumentation by mentioning a study on genetics conducted by Robert Plomin. In the study, the author reveals that genetic heritability accounts for 50% of the psychological differences between us. That leaves 50% which should be accounted for the environment, although most of it is not attributable to environmental influences, but instead it is made up of unpredictable events.

Another supporting argument was cross-cultural research. Personality traits are found to be consistent across cultures, indicating that there is a biological basis for personality. For instance, the Big Five personality traits have been found to be consistent across cultures.

Finally, studies have found that personality traits are associated with specific brain structures and functions. For instance, extroversion is associated with increased activity in the reward center of the brain, while neuroticism is associated with increased activity in the amygdala, which is involved in the processing of negative emotions.

Opposition believes that Twin studies are not an evidence for the nature of influences on personality due to reasons such as: 

  • Small sample size in studies.
  • Equal environments assumption is typically inaccurate. 
  • It is a correlational study not causal.

They proved their belief that nurture forms personal traits by using the example of depression, since it occurs due to the learned helplessness or internal and external influences.

Another point concerns social identity: groups we belong to influence our sense of identity and behavior. Proving that the impact of the environment plays an integral part in upbringing of our personality traits.


The defense of nature influence acknowledges that environmental factors affect personality but even the environmental factors are influenced by personality: personality affects how people construct and perceive their environment. Individuals are differentially exposed to environments depending on their genetically influenced personality.

They protest to the opponents, mentioning:

  • Colorado Adoption Project (CAP) results suggest that parents create the environment for the infant depending on their response to the infants’ genetical characteristics.
  • Hans Jürgen Eysenck, a German-born British psychologist,  argued that some psychiatric disorders can be seen as extreme manifestations of normal distribution of personality traits.

Adding to the argument, the same genes that contribute to personality should also contribute to the psychopathology. Multivariate studies relating personality and psychopathology suggest that there is some genetic overlap between the two domains. For example, a study found that genes influencing anxiety and depression were the same genes influencing the neuroticism dimension of normal personality”.

Nurture team rebutted that brain parts are not evidence to the argument due to the fact that a person can have brain injuries and their personality still does not change.

Schizophrenia studies verify environmental influence: children of mothers with schizophrenia are more likely to develop it due to mother’s behavior.

And so are the children living with the family members who use substances or gamble, they are more likely to behave in the same manner. 

Taking into consideration all these facts, nurture defense states that the importance of environmental factors cannot be argued.


Finalizing the debate, nature group affirmed that certain traits and characteristics are heavily influenced by genetics and are difficult to change or modify through environmental interventions alone.

A study from 2018 concluded that interactions between more than 700 genes had a greater influence on certain personality traits than cultural and environmental influences.

While the environment and every day life experiences may have some impact on personality, they are only secondary to genetic influences.

To top off the argument, Nurture team used examples of Behaviorist nature, such as Watson’s Little Albert and Bandura’s Bobo Doll Experiments, which confirm that behavior is learned from the environment, so that the correlation between upbringing setting and certain personality traits is unarguable.

And not to be forgotten is Freud’s Personality Belief. Freud believed that personality develops during early childhood and that childhood experiences shape our personalities as well as our behavior as adults.


In the end of discussion, listeners were made to vote by using reactions corresponding either to nature or nurture defense. Once results were calculated, it was evident that the nature team won in this ardent debate.

By Iryna Falkivska


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