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What's in a Personality?

heatherl18's picture

 Heather Lewis

Biology 103
Web Paper #2: What's in a Personality?
This summer I went to visit family in Georgia for the first time in about six years. Few things had changed since my last visit; everyone was her usual extroverted, critical, wise-cracking self while I sat silently in my usual corner, nose deep in my newest literary addiction. A journey to a local college with two of my cousins to visit a friend illuminated a curious issue for me. On the way through the dormitory, a young man who had clearly just moved in for the year was unpacking to the music blasting from his stereo. He looked up as we passed; I could barely get my lips to curl into the amiable smile I have to plaster to my face in order to seem less like the social zombie I pretend not to be. My younger cousin, however, had quite a different response. Upon establishing eye contact, she introduced herself and promptly asked this man she had never met before for his phone number. He declined on the grounds that, of course, he didn't know her, but I had to stop and wonder how my shameless, book-hating, laid-back cousin could be so closely related to my cripplingly shy, neurotic, book-loving self.
The genetics portion of high school biology taught us how our genes are responsible for our physical traits, everything from hair color right down to our shoe size. Some of those traits are hereditary-I clearly have my mother's eyes-and some seem to come out of nowhere-how did I get so tall? But no matter what traits we end up with, scientists agree that it's all in the DNA. While the different combinations of dominant and recessive alleles explains how we received our physical traits, there doesn't seem to be nearly so easy an explanation for what we think of as character traits. How could my mother complain quite vocally about the amount of registers open at the bank when I cringe at the thought of having to order a pizza delivery? Is it a result of my quiet home life as an only child, or did I inherit my quiet nature from my great-aunt Rosie? It's the age old question of nature vs. nurture: Are our personalities biologically predetermined or shaped by our life experiences?
To set about answering this question, it seems useful to devise a working definition of personality. When people refer to someone's "personality," they are usually referring to a set of traits that a person tends to exhibit in most situations. There is some debate about the nature of these traits: is there a finite number of traits? Does everyone have a certain type of trait? One theory is the "Big Five" model of personality psychology. According to this model, everyone has five traits, or "dimensions" of personality. These include extraversion, agreeableness, conscientiousness, emotional stability, and intellect. The combination of each of these dimensions makes up a personality, so that a trait like "outgoing" would result in a high extraversion level, while my self-acknowledged neuroticism would result in a low emotional stability level. According to this model (and this quiz:, I am an Open, Agreeable, Conscientious, Neurotic Introvert. Accurate? Probably, but with categories this broad, this model hardly says anything novel or useful. I tend to like Psychology Today's imagery of a "color wheel" of personality. All the hues, or traits, on the color wheel combine to make a shade of personality.
The mere exercise of defining personality has shed light on the difficulties of determining a biological basis. As Davies points out in "Nature vs. Nurture Revisited," there are many things that can impact and influence personality. He cites psychiatric drugs as one of them. Depression is generally viewed by the psychiatric world as a brain disorder, but could that depression be considered a personality trait? If one takes an anti-depressant to overcome the depression, has the medicine changed one's personality? Depression is assumed to have some sort of biological basis, so it seems possible that it could be a personality trait that is hereditary. The same could be true of another mental disorder, such as Attention Deficit Hyperactivity Disorder. Because there does not seem to be a scientific definition of personality, these are certainly traits that a person would regularly exhibit. The implications of this would be important, because they would suggest that we are medically altering negative traits to turn them into more desirable traits.
The nature versus nurture debate rages on, because there doesn't seem to be an answer as to whether there is a biological basis for personality. However, extensive searching has led me to conclude that the reason for the inconclusiveness is related to the fact that there is no viable definition of personality that would lend itself to scientific investigation. Most articles seem to conclude with the idea that who we are is a result of both nature and nurture, that there is some biological basis for the personality we exhibit, but that this is heavily influenced by the environment we grow up in. I would like to assert, however, that we can't know the biological influence of personality until we can define the concept of personality for ourselves. After  all, the biological basis for personality could be on a much smaller scale than what we are looking for. Perhaps instead of "introversion" I have a gene that makes me more sensitive to my inhibitions. Or a natural receptivity to directions. Maybe "personality" itself is inherently nurtured, because it's the way our genes manifest themselves in a given environment.


Paul Grobstein's picture

genes and personality

"Personality" is indeed a somewhat slippery concept, but aspects of it can indeed, like "physical traits" be shown to be influenced by genes.  The operative word here is "influenced," not "determined" (see Genes, Brains, and Behavior).   And the same goes for environment; neither determines traits, both influence them.