Where Does Personality Come From?
There has existed a debate among psychologists for some time about where somebody gets his or her personality. One camp argues for the “trait theory,” which states that internal factors (think genetics) are what shape a person’s temperamental makeup. The opposing side of the argument holds to the “social learning theory,” that personality is molded by forces outside of the person, such as operant conditioning.
This is the classic question of “nature versus nurture,” and it’s a debate that can be held over pretty much any human condition (whether it’s cancer, diabetes, or the common headache). Both what we are made up of (internal, genetics, and so on) and the environment (the external, what happens to us, what happens all around us, and so on) can potentially be involved in any human illnesses or conditions, and this also applies to personality.
The strongest evidence today points to both internal and external factors being vitally important in the creation of a person’s personality. We cannot say that one carries more weight than the other. Studies have consistently shown that genetics account for about 45 to 50 percent of variation in human personality, while the balance is accounted for by forces and events that occur after one is born, and especially during the crucial developmental and formative stages of life, lasting from early childhood to early adolescence.
For example, research studies have shown that even neonates, newborns straight out of their mothers’ wombs, have clear differences in autonomic reactivity and behavior when exposed to stress. There is also research demonstrating a strong hereditary component to personality in monozygotic twins (two people who came from one egg, hence sharing the same DNA) who are raised apart in different environments. But there is also a strong body of evidence demonstrating that healthy nurturing and guidance through experience instill a person’s character, as well.
The reality is that, in every person, both internal and external forces contribute to the development of personality and should be assessed for their relative contributions to an individual’s personality (and, more important, that person’s vulnerability to distress and ability to manage situations that challenge him or her).
There are more and more clues coming out about personality and how it is formed. Functional magnetic resonance imaging (fMRI) allows neuroscientists to see exactly which regions and realms of the brain react to external stimuli and in some cases to what degree. Exciting research is going on that is allowing us to trace traits back to which part of the brain they are emanating from. This kind of scientific work helps us determine how humans interpret a given situation as being good or bad, risky or safe.
A research project out of Stanford University published in the journal Science shows that people will respond to a potentially pleasant object or experience in very different ways based on differences in personality.1 The study looked at people with varying degrees of extraversion (E), as determined by formal personality testing. All of the participants in this study were shown multiple pictures of happy, sad, and angry faces while being scanned by an fMRI machine. All of the participants, both the extroverts and introverts, had a little pea-sized area of their deep brain (core), called the amygdala, light up whenever they saw a hostile or angry face. But only in the extroverts did the amygdala light up when sad faces were shown. This study may not seem like much, but it helps us understand that who we are as people (that is, our personalities) is clearly hard-wired into certain areas of our brain and is at least partly determined by biological causes. The brains of extroverts and introverts do not work in quite the same way.
And yet there is also plenty of research from the school of social psychology showing that personalities are shaped by societal and social situations that people find themselves in, and that they are affected and developed by personal histories. Or, as Shakespeare put it, “all the world’s a stage, and all the men and women merely players.” Meaning that we are what we play. We all take on and play many roles in society, and these social roles do, to some extent, shape our identity.
Each role we play brings with it certain rules or expectations about how we should behave and react in certain situations. A good research study demonstrating this was the famous “prison guards” experiment that looked at how people behave when arbitrarily assigned to roles as either a guard or a prisoner.
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