October 3, 2012
Study Says Genetics Of Intelligence Remains A Riddle, For Now
April Flowers for redOrbit.com - Your Universe Online
Your intelligence — like almost all other traits — is a gift from your parents, at least in part. Scientists have known for a long time that intelligence is at least partially inherited through genetics. According to psychological scientist Christopher Chabris, however, it may be some time before researchers can identify the specific genetic roots of intelligence.
A new study from Union College shows that the genes long thought to be linked to intellectual prowess actually appear to have no bearing on one's IQ, complicating scientific endeavors to get to the root of the genetics of intelligence.
An international team of researchers including Harvard economist David Laibson used large data sets that included both intelligence testing and genetic data to examine a dozen genes. In almost every case, the team found that IQ could not be linked to the specific genes that were tested.
“In all of our tests we only found one gene that appeared to be associated with intelligence, and it was a very small effect. This does not mean intelligence does not have a genetic component. It means it´s a lot harder to find the particular genes, or the particular genetic variants, that influence the differences in intelligence,” said Chabris. The results of this new study were published online in the journal Psychological Science.
Previous studies of identical and fraternal twins informed and bolstered the notion that intelligence is a heritable trait. This new research validates that conclusion, yet the exact parameters of the genetics of intelligence remain a mystery. The team asserts that the older studies, which picked out specific genes, had flaws because of the technological limits of the time. Those limits prevented researchers from probing more than a few locations in the human genome to find genes that affected intelligence.
“We want to emphasize that we are not saying the people who did earlier research in this area were foolish or wrong,” Chabris said. “They were using the best technology and information they had available. At the time, it was believed that individual genes would have a much larger effect – they were expecting to find genes that might each account for several IQ points.”
The team says that much more research is needed to determine the exact role that genes play in intelligence.
“As is the case with other traits, like height, there are probably thousands of genes and their variants that are associated with intelligence,” he said. “And there may be other genetic effects beyond the single gene effects. There could be interactions among genes, or interactions between genes and the environment. Our results show that the way researchers have been looking for genes that may be related to intelligence – the candidate gene method – is fairly likely to result in false positives, so other methods should be used.”