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Genetics, Personality, and You

by on March 6, 2012

    By Margo Bergman

People say you have your mother’s eyes, your grandfather’s chin, and your father’s tendency to clean obsessively. Although you may have thought that the last one was because you grew up with the fear that if you set a glass down, it would be snatched away to the dishwasher, new research shows that you may have inherited your affinity for daily vacuuming, and other personality traits, in same way you inherited your gorgeous baby blues.

Study

A recent study concludes that up to 35% of certain personality traits, such as neuroticism or extrovertedness, can be attributed to genetic factors rather than the social influence of family members. These genetically-linked personality traits, called “The Big Five,” influence a person’s interest in various activities, such as manual labor, creative arts, or logical thinking.

To deduce whether various aspects of personality originated through genes or by social influence, the authors interviewed 422 sets of twins, both identical and fraternal, as well as the twins’ family members and friends.

A genetic predisposition manifests through internal reward circuitries, or brain chemistry, which kick in when a person engages in certain activities, whereas social origins for behavior work through external rewards, such as praise.

For example, if you have a genetic predisposition toward excessive cleaning, then loading the dishwasher will trigger the brain to release feel-good chemicals while engaging in that behavior. If the behavior is not genetic but social, then the reward will from outside, when your parent compliments you on your tidy sock drawer.

Genetic predispositions are what guide people towards certain interests, is the suggestion put forth by Christian Kandler and colleagues at Bielefield and Saarland Universities, in their recent paper “The Genetic Links Between the Big Five Personality Traits and General Interest Domains” published in December 2011 in Personality and Social Psychology Bulletin. Researchers within the discipline are conflicted as to whether interests are an expression of our personality traits, or an independent variable. Kandler’s study is designed to answer this question, as well as determine the specific genetic links to both personality traits and interests.

courtesy of stock.xchng

Twins

Using both fraternal and identical twins in the study created a control group which helped the researchers differentiate between environmental and genetic origins for traits. Identical twins share the same genotype, so if they differ in a specific personality trait then it is unlikely that the trait is genetic. Fraternal twins, while genetically no different than siblings, are considered to have more similar environmental effects than traditional siblings. Differences in identical twins show the effects of environment, while differences in fraternal twins can give light to a root genetic cause.

Still up to you

Lest you fear, then, that your genes will cause you to descend upon every dirty glass within 23 seconds of it being set down, the authors note that a genetic predisposition is not a guarantee of behavior. Kandler et al notes “People would not develop intrinsic motivation for an activity such as playing guitar or football without any (musical) talent or athletic abilities and reinforcement by developing mastery.” The internal motivators determined by your genetics still require development by practicing.  However, this research does strongly imply that in order to overcome our genetic tendencies, we must be highly motivated by an external reward, such as love or hatred, that is stronger than the internal ones that feeds our genetic personality type. The question of the role of nature versus nurture in shaping personality is still relevant. It’s also still true that the obsessive cleaner doesn’t fall far from the dishwasher.

Margo Bergman is a Ph.D. Economist turned public health genetics researcher. Her main interest is helping people make better decisions about their health based on genetic information. Her secondary interests include baking and ponies.

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