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Influence of Traits and Biology on Personality Development


Who I am? What is it that affects my actions? Am I doing what I really want to do, or is there an invisible force, internal or external, driving my actions and fooling me into thinking that it is me who is the captain of my life? Sometimes under the influence of extreme anger, we think and ask ourselves ‘that was not me’, or ‘I was out of character’. These are a few questions regarding the development of our personality and the old age bifurcation of nature vs. nurture. These questions are very important, and every human being asks himself or herself these questions throughout the course of his or her life. There are no straight answers to these questions, and the debate is ancient in human intellectual history that dates back to the ancient Greeks and thinkers like Plato and Aristotle. Hence, the debate is still here, puzzling and amazing us with its complex implications and repercussions that do not provide a simple answer but force us to ask more questions that, in turn, lead to further questions. This chain of questions and no specific answers do not mean that the debate is a waste of time, on the contrary, it introduces to the more insightful, deeper, and uncanny nature of human existence and the world we live in.


Therefore, the purpose of this essay is not to give you the hard, fast rules about the development of human personality but to introduce the reader to this ongoing debate that does not cease to amaze us due to the open-mindedness and ambiguous nature of this debate. In the course of this essay, we will first examine the influence of gene-environment interaction on human personality and the cultural factors that influence personality development. Similarly, we would also examine the twin studies and their influence on inheritability on human personality. Furthermore, we would also see the features of temperament regarding its contribution to adult personality and its constancy and variability over time.

The most important thing regarding the knowledge of personality development as I have already referred in my introduction about the two sides such as nature and nurture, the gene-environment interaction emphasizes that both genes and environment contribute in the development of our personalities. Second, genetic and environmental influences are not independent; the effect of one variable depends on the other. For example, human beings have the natural tendency to kill their fellow beings, but this natural instinct does depend on external factors and, more specifically, the stimuli that are provided through the environment. Hence, their dependency is a crucial concept to understanding gene-environment interaction studies in personality development.

This interaction between genes and the environment is commonsensical. For example, in Joseph Conrad’s Heart of Darkness, there is a sequence where an Englishman kills a Congolese merely for the reason of telling him the wrong price of the hen, and according to Conrad, that man was regarded as ‘the gentlest and kindest man ever walked on earth. Hence, our environment controls our genes; hence, ‘in essence, it is only when adverse environmental conditions are experienced that the genes come online’ (Dick and D.M, 2011). A recent study has also introduced a new term known as ‘plasticity genes’; according to this idea, the genes that are negatively affected by adverse environments are likely to benefit more from the positive environment (Belsky J et al., 2009).

Twin studies are the most important of all in order to investigate the insights into the nature versus nurture argument. As far as the twin studies are concerned regarding the inheritability of personality, results show variations. According to this study, the environment plays an important role in controlling genes. For example, the individual who has a low genotype of extraversion would be low on extraversion if predisposed to an environment that is very organized and suppressive, while on the contrary, the individuals who have a high score on extraversion trait would score high regardless of their environment. In the second case, the individual who has a genotype of high impulsivity trait would increase this impulsivity if predisposed to a conflict-filled environment (Bergeman et al., 1988).

Temperament is defined as the emotional reaction that one shows towards his/her environment. It is very difficult to answer this question by referring to the simple categorization of the things that stay stable and the things that change over time; nevertheless, some temperaments that stay stable over time contribute to personality development in adults. For example, introverts are to stay introverts for the rest of their lives, while in some cases, introverts seem to get out of this psychological condition. However, some people argue that the brains of introverts are wired the way they cannot bear the burden of sociability and hence are forced into isolation, friendliness, and emotional anxiety. Similarly, there are many psychological issues involved in the development of our temperament in our early childhood, which is also known as the Freudian subconscious. These childhood traumas develop one’s temperament which is lifelong and unchangeable in the case of many individuals, sometimes it is positive and productive for individuals (artists) and other times it can be fatal and painful (cases related to sexual abuse and child molestation).

Culture plays an important role in the development of our personalities; culture programs our minds, and our minds are easily manipulative and can be controlled accordingly. I gave an example of a character from Conrad’s novel. What were the things that resisted him from acting nicely in England while mercilessly in Congo? I think the answer is the culture that consists of values, law, and, most of all, law enforcement institutions; the moment you have removed these institutions that inflict or try to inflict order, you are exposed to your real nature, the nature of an ape who can kill if opened into the wilderness of Africa. The Lord of the Flies is another beautiful work of art that deals with this issue of cultural and institutional programming in human societies.


The brief summaries that I have provided so far are a small attempt to understand human nature and its working in the environment he/she lives in. The studies we have discussed give no black-and-white answer to the posed questions of what contributes to the development of human behavior and human personality. In some cases, genes seem to rule our behavior, while in other cases, it is the environment, while in other cases, it is both environment and genes that stimulate human behavior. Hence, there will never be any study that can give a closed-ended answer to the mysteries of human personality and its make but the chunks of studies that rationalize it on a case-by-case basis.


Belsky, J., Jonassaint, C., Pluess, M., Stanton, M., Brummett, B., & Williams, R. (2009). Vulnerability genes or plasticity genes?. Molecular psychiatry, 14(8), 746.

Bergeman CS, Plomin R, McClearn GE, Pedersen NL, Friberg LT

Cervone, D., & Pervin, L. A. (2015). Personality, binder ready version: theory and research. John Wiley & Sons.

Dick, D. M. (2011). Gene-environment interaction in psychological traits and disorders. Annual review of clinical psychology, 7, 383-409.

Psychol Aging. 1988 Dec; 3(4):399-406.



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