Study Says Prenatal Environment Plays Important Role in Child's Intelligence

A child's intelligence may have less to do with the genes inherited from his or her parents - and more to do with its prenatal environment - than previously believed, according to researchers from Carnegie-Mellon University in Pittsburgh.

In a study for the journal Nature, the researchers say the genes from a child's parents may only account for as much as 50% of intelligence - in fact, the researchers think it's more likely to be even less of a factor because of some similarities in the genes of both parents.

On the other hand, the researchers say their studies indicate that the quality of their stay in the womb accounts for 20% of the similarity in intelligence among twins and 5% of the similarity among siblings. Previously, scientists have not given much credence to the idea that what's described as "maternal effects" have any bearing on a child's intellect.

Generally, what all this means is that - in the view of the researchers - the argument over whether intelligence is determined by "nature," in the form of genes, or "nurture," as a result of a child's environment, goes to the "nurture" forces. But it's not quite in the way most scientists pictured it - the researchers say the maternal effects seem to play a more important role in determining intelligence than even the home environment of a child.

The researchers say the study some important implications for society at large. For instance, they suggest that one reason certain minority groups and poor people don't test as well as others may be due to inadequate prenatal care rather than some of the racial theories offered in recent years.

"It will be important to understand the basis for these maternal effects if ways in which IQ might be increased are to be identified," the Nature editors say in a synopsis of the Carnegie-Mellon study.