Everyday Psychological Traits

By assigning a simple percentage to something very complex and poorly understood, behavioral geneticists turn heritability into a clear-cut measurement. Behavioral geneticists have employed these same statistical techniques with ordinary behaviors and attitudes. The resulting list of traits for which heritability has been calculated extends from such well known areas as intelligence, depression, and shyness to such surprising ones as television viewing, divorce, and attitudes like racial prejudice and political conservatism.

Such heritability figures may seem quite remarkable, even incredible. Behavioral geneticists report that half of the basis of divorce, bulimia, and attitudes about punishing criminals is biologically inherited, comparable to or higher than the figures calculated for depression, obesity, and anxiety. Almost any trait seemingly yields a minimum heritability figure around 30 percent. The heritability index acts like a scale that reads 30 pounds when empty and adds 30 pounds to everything placed on it!

Believing that basic traits are largely predetermined at birth could have tremendous implications for our self conceptions and public policies. Not long ago, an announcement of a government conference, for example, suggested that violence could be prevented by treating with drugs children with certain genetic profiles. Or parents of children with an alcoholic heritage may tell the children never to drink because they’re destined to be alcoholics. But such children, in expecting to become violent or drink excessively, may enact a self-fulfilling prophecy. Indeed, this is known to be the case. People who believe they are alcoholic drink more when told a beverage contains alcohol–even if it doesn’t.

Believing the heritability figures developed by behavioral geneticists leads to an important conclusion: Most people must then be overestimating how much daily impact they have on important areas of children’s development. Why ask Junior to turn off the TV set if television viewing is inherited, as some claim? What, exactly, can parents accomplish if traits such as prejudice are largely inherited? It would not seem to matter what values we attempt to convey to our children. Likewise, if violence is mostly inbred, then it doesn’t make much sense to try to teach our kids to behave properly.

From Fatalism to Depression

The vision of humanity generated by statistical research on behavioral genetics seems to enhance the passivity and fatalism many people are already saddled with. Yet evidence gathered by University of Pennsylvania psychologist Martin Seligman, Ph.D., and others indicates that “learned helplessness” — or believing one can’t influence one’s destiny — is a major factor in depression. The opposite state of mind occurs when people believe they control what happens to them. Called self-efficacy, it is a major contributor to psychological well-being and successful functioning.

Is there a connection between the increase in depression and other emotional disorders in 20th-century America and our outlook as a society? If so, then the growing belief that our behavior is not ours to determine could have extremely negative consequences. As well as attacking our own sense of personal self-determination, it may make us less able to disapprove of the misbehavior of others. After all, if people are born to be alcoholic or violent, how can they be punished when they translate these dispositions into action?

Jerome Kagan, whose studies provide a close-up of the interaction of nature and nurture and how it plays out in real life, worries that Americans are too quick to accept that behavior is predetermined. He has studied the temperaments of infants and children and found distinctive differences from birth — and even before. Some babies are outgoing, seemingly at home in the world. And some recoil from the environment; their nervous systems are overly excitable in response to stimulation. Do such findings mean children born with a highly reactive nervous system will grow into withdrawn adults? Will extremely fearless children grow into violent criminals?

In fact, less than half of the reactive infants (those who more frequently fret and cry) are fearful children at the age of two. It all depends on the actions parents take in response to their infant.

Kagan fears people may read too much into children’s supposedly biological dispositions, and make unwarranted predictions about how they will develop: “It would be unethical to tell parents that their three-year-old son is at serious risk for delinquent behavior.” People who are more fearful or fearless than average have choices about the paths their lives will take, like everyone else.

    Last reviewed: By John M. Grohol, Psy.D. on 30 Jan 2013
    Published on PsychCentral.com. All rights reserved.