Tuesday, August 01, 2006

Nature and Nurture in IQ Scores

Since many gifted programs use IQ scores to judge admission, people attach great importance to the number. They also spend a lot of time debating nature vs. nurture. Children from well-to-do families broadly have higher tested IQs than those from less well-to-do families. But are people well-to-do because they have higher IQs, and so pass these intelligence genes on to their children, or do well-to-do families give their kids lots of opportunities, which raises IQs?

Identical twin studies over the past century have reached a conclusion that about 75% of IQ is a result of nature (genes) not nurture. But an interesting recent article in the New York Times called After the Bell Curve suggests that viewing nature and nurture as separate forces is misleading.

Scientists have been discovering over the past few years that we can actually turn on and off gene expression through our behavior. My husband told me about a recent study on shyness genes that found approximately the following (I'm trying to remember the numbers right and can't guarantee accuracy, but they're not far off): Of people who are shy, 90% have a certain gene. But of people who have that gene in the broader population, only 50% are shy. Apparently, if you have the gene to be shy, but your parents don't let you hide around their legs in social situations, and make a point of making you play with other kids, you won't necessarily grow up shy. Even though your genes would seem to indicate you would.

IQ scores follow a similar pattern. A child who would naturally have a high IQ who is born into a family of professionals who read to him, talk to him, ask him questions and otherwise encourage his little brain to grow, will express those genes for intelligence. A child who would naturally have a high IQ who is put in, say, an orphanage where children do not receive enough attention, will not express those genes for intelligence. A child who would naturally have a lower IQ who is adopted into a high-IQ family will still have a lower IQ than the rest of the family (as the twin studies have shown). However, if his parents provide an enriched environment, his IQ will be somewhat higher than if he'd been in a family that didn't provide such an environment.

The problem with finding that nature and nurture both matter is that people can use that reality to justify whatever they want. One could certainly make an argument in favor of early interventions for babies and toddlers in at-risk families. Providing them with an enriched environment could allow these children to express any genes for intelligence they have.

On the other hand, plenty of parents of gifted kids have been told by teachers that differences in abilities exhibited by children in kindergarten don't matter, and shouldn't be addressed, because "they all even out" over time. If nurture matters, and the teacher plans to provide a very enriching environment, she may believe that overcoming all IQ differences is possible (even though that's not what any of these studies show).

But parents of gifted kids could also use the nurture argument to their advantage. Children with naturally high IQs who are put in more enriching classes are more likely to express these genes. That seems to be a good argument for better gifted education. These kids can't be left to "fend for themselves." If they are, their actual intelligence will be less than it could be.

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