Between Nature and Nurture: A Discussion on the Sculptors of Our Personalities

For countless years humanity has asked itself what made us who we are. Why are some of us thieves and murderers, whilst among them also exist those who would lay down their lives for a reward they would never see? This question, and many more like it, has prompted numerous, often contrasting answers concerning the processes which shape our unique personalities—some proposing that it there might not be processes at all.

Christianity, Catholicism, Islam, and various other religions purport that we become whoever any one of their gods want us to be. How we think, feel, act, are all already decided before we were even born. The only element that could possibly change the nature of a man, are the interventions of the divines. Or at least, that’s what their scriptures say.

While the pseudoscience of eugenics similarly suggests that our personalities are completely sculpted in the womb. Our genetic heritage dictate the kinds of persons we will turn out to be, and there is absolute nothing we can do to change the outcome. Racists and bigots—to take an extreme example, people akin to Adolf Hitler—adhere to this view, deluding themselves into thinking that certain races are born in higher stations, and the rest in lesser places.

Yet there exists what is called the Blank Slate theory, often known by the more decorated name of Tabula Rasa. Within its perspective, each human being is born without any psychological trait, and that these characteristics are instilled only via the process of growing up. The environment plays the role of gods in this view, as the theory posits that we are all infinitely malleable to the peoples, happenstances, and whatever other affecting factors floating in the atmosphere around us.

Then there is the Noble Savage literary concept turned into something of a theory; an idealistic claim that states humans are inherently good and kind, it is just society ruined the inherent goodness in our hearts. Many would like to believe in this ideal—myself included—unfortunately it has next to no supporting evidence. Contemporary nomadic tribes living outside of modern civilization, the supposedly corrupting force, regularly commit genocide, and the intact remains of our long-gone ancestors showcase plethoras of battle wounds—discrediting the hypothesis in its entirety (Pinker, 2002).

But which of the above supposition are true? Are we destined to be as nature designed us, be it good or evil? Or are we like the moulds of sculptures, able to be shaped in whatever fashion the environment desires? The answer, rather unsurprisingly, lies somewhere in the middle of these two extremes.

In 1998, the psychology researcher Judith Rich Harris developed what she calls the Group Socialization theory; outlined in her book The Nurture Assumption: Why Children Turn Out the Way They Do. According to her idea, we neither have genetic or supernatural destinies, nor are we so easily influenced by the things around us. Both nature and nurture—i.e. the environment—play crucial roles in shaping our personalities. Furthermore, the two may have equally powerful impacts on our psyches (Harris, 1999).

Harris arrived at the conclusion of nature and nurture sharing the same power in the development of our minds via identical-twin studies. Or more precisely, the pairs who where separated shortly after birth, by adoption or other causes. These researches provide crucial information for allowing scientists to designate which parts of our personality are genetically transmitted.

At this point of the discussion, we should dismiss the idea that people are completely blank slates. Analyses conducted on families, siblings, cousins, and so on have revealed that some traits—such as temperament, sociability, and such likes—are passed down via genetic means (Pinker, 2002). Though this transmission is by no means absolute, as the process of reproduction is complicated by factors the likes of mutations and the presence of alleles; to an extent randomizing the genetic make-up of an offspring. However, twin-studies have the potential to indicate exactly how much the randomization affects a child, but they once had a debilitating limitation: they cannot pinpoint precisely which items are genetically heritable, or are the results of being raised in similar environments.

Hence, Harris wisely examined the twins who were separated at birth. By examining sets of twins who grew up in separate, and potentially very distinct environments, she could more accurately identify the traits that are genetic, and the ones carved by the chisels of the environment. Her findings are nothing short of surprising.

From a list concocted from psychological tests (whose names I’ve stupidly forgotten, but can be found in Harris’ book) designed to find similarities between persons, separated twins have been found to be more attuned to one another than any other pair of humans. Ranging from political views, levels of attachment to romantic partners, tastes in music, and so on, the twins harbor a fifty-percent rate of correlation. That is, half of their respective traits can be found in their counterparts—something that cannot be said even for fraternal twins raised in the same household.

What makes Harris’ discoveries worthy of utmost attention though, are the implications they generate. From her observations, Harris concluded that nature and nurture have a fifty-fifty divide over how much influence they hold over us. I.e. we are the results of the collaboration between our parents’ genetic legacy, and the people and objects the environment has placed around us. And quite surprisingly, parents have little to no influence on us. Each of these statements of course require some degree of explanation, lest they be considered overtly ambitious fabrications.

Firstly, let us consider the children of an immigrant family. Do they use the language, accent, and fashion-styles of their parents, or do they instead adopt the norms of the native children surrounding them? We’ve all been children, and some of us probably have only just reached adulthood, we know what it’s like to so desperately want to “fit in.” But to do so, these immigrants would have to instill the culture foreign to their parents. Humans are social creatures, after all, and we grow distressed each time we’re treated as outcasts. In the eyes of our anatomy, we begin to produce stress hormone the likes of cortisol (Gruenewald, Kemeny, Aziz, 2006).

From an evolutionary standpoint, humans lack the strength, razor-sharp fangs, and stocky hides of our competitors. For our long-gone ancestors to have survived—all the while successfully reproducing—the harsh tests concocted by Mother Nature, they had to band together. The production of stress hormones when failing to find cooperative partners is the evolutionary incentive we have to urge us into bonding with fellow humans, and punish those who might have preferred isolation. Such is the cold logic of evolution.

Adaptability, in terms of sociability, has been crucial for the success of our species. We humans have always had to use our genetic gifts, and the things we have, especially people, around us to thrive. Hence, the fifty-fifty division. If we had been “designed” by evolution to use only one of the tools available to us, and how they influence the kind of person we’d eventually become, we would not have reached the heights we’re in today. Why the environments has so much power over our members is a consequence of our now extremely refined survival strategy. Thus, an exactly equal percentage of shares might not be the most precise measurement, but it does reflect the reality of it all.

Further arguments can be made by observing the development of individual humans. As we grow older, we rake in more and more of the harbored by the people around us; teenagers who smoke and drink because their friends do, tastes in clothing as dictated by what is popular among our peers, et cetera.

As for our genes, they’ll stay the way they’ve been from the wound until the end of our lives. We carry the same propensities throughout the years, for intelligence, competitiveness, and other genetically-heritable traits. Yet for the sake of social acceptance, we control how conspicuous our genetic perks are; much like the people who pretend to be as clueless as those around him, even though he’s actually far brighter, or the guy who nods along in the conversation without understanding a single point said in the discussion. To put it simply, we control out starting personalities to make them more acceptable to the people we meet.

Now for the case of parental influence, there are good reasons to consider it negligible. Since, as we continue to mature, we begin to stray away from the need to constantly be protected by our parents. Independence is  an essential element of adulthood, and as a consequence, one ceases to be in the same environment as that of his or her parents; letting the nurture part of development be under the control of wherever we end up in. But this is not to say that parenting is an ignoble task.

Parents are charged with the caring of hapless, helpless children. Their duty is to ensure that these vulnerable humans one day turn out to be a contributing member of society—perhaps more. Moreover, they are also responsible for the happiness, health, general welfare of their offspring. But how to do so, given that evidence suggests their influence wanes away rather quickly? As a starting point, parents can select what kind of environments their children would be in. If they can manage a strong relationship with the child, then they could potentially be one of the peers considered influential to the development of the child. These are the options parents have, though I admit they might be incomplete since I do not yet have a child, but they are valuable and powerful ones.

With that note of gratitude for parents–including mine–concluded, we can continue discussing the subject at hand.

Who we are, and what we’ll become, is next to unpredictable. The factors of genetics alone complicates matters to the point of being nearly incomprehensible, add to it the ever-changing elements of culture, and we might as well declare that we can never be sure as to who will be what. An excess of components to consider virtually makes it indeterminable to foresee an individual’s future.

But I consider Harris’ research to be a bright light in a world desperate for one. Her work means that there are always possibilities for us to rise above our stations, to be more than what our strands of DNA, where and when we were born, commanded us to be.

Humans have for millennia held one particular advantage over the other creatures of the animal kingdom, one that has allowed us to prosper over all these years: we can adapt to almost any possible situation presented to us. Uncertainty lets in the possibility for success against all odds. And justifies the most naive ambitions we hold in our hearts. Harris’ research elegantly reaffirms this hopefulness, and it is one that I am very appreciative of.



Gruenewald, Kemeny, Aziz. 2006. Subjective social status moderates cortisol responses to social
threat. PubMed. Retrieved from

Harris, Judith R. 1999. The Nurture Assumption: Why Children Turn Out the Way They Do. New York: Free Press.

Pinker, Steven. 2002. The Blank Slate: The Modern Denial of Human Nature. London: Penguin Books.


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