Key Concepts

• Researchers have powerful new technologies to probe genes and the brain, looking for the basis of intelligence differences among individuals.
• Their work is providing a new understanding of what intelligence is, while also revealing unanticipated complexity in the interplay between genes and environment.
• The more scientists learn about the role of genes in intelligence, the more mysterious it becomes, but the quest is still worth pursuing.

In Robert Plomin’s line of work, patience is essential. Plomin, a behavioral geneticist at the Institute of Psychiatry in London, wants to understand the nature of intelligence. As part of his research, he has been watching thousands of children grow up. Plomin asks the children questions such as “What do water and milk have in common?” and “In what direction does the sun set?” At first he and his colleagues quizzed the children in person or over the telephone. Today many of those children are in their early teens, and they take their tests on the Internet.

In one sense, the research has been a rousing success. The children who take the tests are all twins, and throughout the study identical twins have tended to get scores closer to each other than those of nonidentical twins, who in turn have closer scores than unrelated children. These results—along with similar ones from other studies—make clear to the scientists that genes have an important influence on how children score on intelligence tests.

   
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