Nature vs. Nurture: A Continuing Debate

Sarah Harding's picture

What has a greater effect over our lives: genetics or environment?  Unfortunately, this is a question with no answer.  The nature versus nurture debate has been continuing since the time of Aristotle, and yet, we are no closer to determining the truth.  Each side has valid points that any sane person is unlikely to dismiss.  Therefore, the debate is unlikely to end soon.  For now we will have to accept that our personalities and tendencies are a combination of genetics and environmental influences. 


            In certain situations, it is obvious that genetics have a greater role in shaping one aspect of a person.  In the example of smoking, some people believe that the desire to smoke is pre-determined by our genetics, while others believe that outsiders (such as peers or tobacco companies) have a greater influence.  In tests with twins, the effects of environment are easier to study because the issue of genetics has been neutralized.  It was discovered in these studies that “different versions of the gene CYP2A6 dictate the number of cigarettes a person smokes.”[1]  Apparently, this gene determines how quickly one metabolizes nicotine, and how often they need to light up.  Does this exonerate the tobacco industry?  Not quite.  Further studies have shown that women are more likely than men to be affected by their environment to begin smoking.[2] Where does that leave us?  In that same place as everyone else involved in this debate.  While there is evidence that genetic pre-determiners exist for certain behavior (for example: smoking habits), if the environmental effects do not occur, then the genetics will never take over.  For example, in the case of a person whose family has a disposition towards alcoholism: If they are raised in a household without access to alcohol, they will never experience the habits of alcoholism. Thus, the debate remains open. 


            What would happen if genetics could be altered by the environment?  This discussion would no longer be a clear-cut nature vs. nurture.  We are born with synaptic links that are pre-programmed with our genetics.  However, experiences (eg. impacts from the environment) can affect these synapses.  The intensity of the gene expression can be changed so that we act differently in the world.  This is sometimes referred to as “synaptic plasticity.”[3]  An example of this is fear.  We have an innate sense of fear that is encoded in our DNA. We unconsciously understand that if something is going to harm us, we should be afraid of it.  However, our environment serves to show us what to be afraid of.[4]  It seems as though “genes are not immutable things handed down from our parents like Moses’ stone tablets but are active participants in our lives, designed to take their cues from everything that happens to us from the moment of our conception.”[5]Which has a stronger effect on us: genes or environment? Which came first: the chicken or the egg?


            It was once revealed in 2001 that environment was the key indicator of human behavior.  In clear print the entire world was to believe the no matter their genetics, environment had all the effect.  When the human genome project was completed, it was revealed that there were 30,000 genes instead of the predicted 100,000.  Therefore, many scientists declared that there couldn’t possibly be enough genes to make each person unique.  If we were greatly affected by our genes, and there weren’t enough genes to make each person different, then we would all act the same.[6]  While this is an interesting theory, it is statistically insignificant because there are billions of combinations that can result from 30,000 genes.  However, one significant observation is that environmental influences are often more permanent than genetic ones.[7]  Perhaps because the environmental impact is more powerful, it is misconstrued as being greater.  Genetics and environment however, are dependent upon each other; without the other, they would not exist. 


            The potential reason for this continuing debate is man’s desire to exonerate himself of blame for his behavior.  If certain behavior, such as a predisposition for drinking or smoking is related to genetics, then the person cannot be blamed for his behavior.  After all, it’s human instinct to protect oneself.  Unfortunately for these people, however, the conclusion of most scholarly work is that while genes provide the bases of our behavior, without certain environmental impacts, these predispositions will remain untouched.  As Ridley reminds us, “these genes are at the mercy of our behavior, not the other way around.”[8] What’s also interesting is that the genes themselves allow the brain to learn.  Without the genes, we wouldn’t be able to adapt to situations, or to allow our environment to affect us.  How strange that environment and genes are closely connected in this circle. 


            While anthropologist Fraz Boas tried to convince that world that environment was the sole contributor to human behavior, scientific research has shown that to not be true.  In fact, our behavior is shaped by a combination of genetics of environmental influences. Neither can function on its’ own, and neither can influence us on its own.  While the debate still continues, and scientific research will continue to be done, we should operate on the assumption that we are complicated creatures that require more than one stimulus.  It would be easier to believe that our surroundings are responsible for our behavior, but at least a portion of it must be contributed to inheritance.  Thus, the debate continues…

[1] Bryner, Jeanna. “Nature vs. Nurture: Mysteries of Individuality Unraveled.” Live Science. 19 July 2006.

[2] Ibid.

[3] LeDoux, Joseph. “Nature vs. Nurture: the Pendulum Still Swings With Plenty of Momentum.” Chronicle of Higher Education. 11 December 1998.

[4] Ibid.

[5] Ridley, Matt. “What Makes You Who You Are.” Time Magazine. 25 May 2003

[6] Ridley, Matt. “What Makes You Who You Are.” Time Magazine. 25 May 2003.

[7] Ibid.

[8] Ibid.


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