On Nature vs. Nurture, Success and Failure

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Almost everyone remembers doing the obligatory science experiment where two identical seeds (mine were lima beans) are grown under different conditions and monitored daily. The ambitious among us may have tried this experiment with several different types of plants to determine if some plants are “heartier” than others (i.e., they withstand more abuse or respond faster to attention). None of us, I suspect, thought that these experiments were anything more than opportunities to use the scientific method to prove an obvious fact: that nature and nurture interact.

The human nature-nurture debate, however, has been a timeless source of controversy. It is fueled by the fact that families’ basic nurturing capacity varies enormously by race and class, and fanned by the fact that arguments behind most social programs for the poor rest implicitly or explicitly on the assumption that it is possible to close performance gaps through such social interventions as Head Start.

Charles Murray and Richard Herrnstein lobbed the last big serve against social interventions in 1994 with The Bell Curve, in which they argued that genetics explain most of the differences in people’s intelligence – which opened the door for renewed claims that minorities are genetically inferior.

Eric Turkheimer, a University of Virginia psychologist, is sending a lob back with a soon-to-be-published study that confirms that what happens to plants happens to children. Using IQ scores as the proxy for nature and socioeconomic status as the proxy for nurture, Turkheimer and his colleagues looked at the influence of genes on intelligence among very poor, mostly African-American children – the plants grown under the stairs and in the closet.

Using a large national database, he identified more than 620 pairs of twins who were born in the 1960s and given IQ tests at age 7. By looking at the differences between identical and fraternal twins, he concluded that the importance of environmental influences on IQ is four times stronger in poor families than in affluent families. Conversely, the heritability of IQ is seven times stronger in wealthy families than in poor ones. (See the forthcoming November issue of Psychological Science.)

Put simply, in an environment of educational and social abundance, the extra efforts wealthy families make to improve on the genes passed on to their children have relatively little impact. But in environments defined by scarcity, there is quite a lot that parents, program providers and policy-makers can do to ensure that children reach their potential. When it comes to the spectrum of socioeconomic class, nature matters more on the high end and nurture matters more on the low.

What do we do with this new evidence that nurturing matters?

First, recognize that this is just one of several studies reinforcing the importance of nurturing. The Turkheimer study focuses on the gross importance of family capacity on intelligence. Other studies, like “Hardwired to Connect,” the recent report from the Commission on Children at Risk, emphasizes the important long-term role that nurture plays in reducing mental, behavioral and emotional problems among youth, and in promoting youth development. (It’s available for purchase at www.americanvalues.org/html/hardwired.html.)

“Positive nurture,” the report asserts, “has the power not just to counter ‘bad genes’ but also – at the biological level – to change the way particular genes operate so that what would otherwise be genetic vulnerabilities are neutralized or even transformed into strengths.”

Second, and most important, we need to recognize that our interventions are often too little, too late, and too selective to address the cumulative nurturing imbalances.

Maybe this new evidence will spark renewed efforts against tendencies to address problems one at a time or to inadequately fund successful programs. And maybe it will shed light on the more insidious practice of “selective nurturing.”

Let me explain:

None of the systems that fail to nurture poor and minority children and youth fail all of them. There are those youth who, for whatever reasons, are selected for or seek special attention. They find their way into the “beat-the-odds” stories highlighted in columns and conferences. They beat those odds by finding someone to nurture them.

These stories warm our hearts, but they have a fatal flaw – they rely on the child to have the spark, the magical smile or the life-changing event to get the attention of the adults – parents, teachers, youth workers, ministers, judges, social workers, corrections officers, coaches and neighbors.

This is far too heavy a burden to place on our children.

Karen Pittman is executive director of the Forum for Youth Investment. This article and links to related readings, including the e-mail conversation described here, are available at www.forumforyouthinvestment.org.