New Study Challenges Gene-Personality Link
Earlier this year scientists thought they’d found a gene that might influence how impulsive, excitable and quick-tempered a person is. Now they say they can find no evidence that’s the case.
That still doesn’t mean the initial finding was wrong, said Dr. Anil Malhotra of the National Institute of Mental Health, an author of the new study. It does mean it’s time to take another look at the earlier work, he said.
Two reports published in January gave evidence that the so-called DRD4 gene influenced a trait called novelty-seeking. People scoring high in this trait were found to be impulsive, fickle, excitable, quick-tempered and extravagant. Those scoring low tend to be reflective, rigid, loyal, stoic, slow to anger and frugal, researchers said.
The studies were the first confirmed association between a particular gene and a normal personality trait. The main study, done on Israelis, was conducted by a team led by Richard Ebstein of the Sarah Herzog Memorial Hospital in Jerusalem. Similar results came from a second study done at the National Institutes of Health.
The evidence for the gene’s effect was statistical. The studies found that, on average, people with a particular variant of the gene scored about 10% higher for novelty-seeking on personality tests than people who lacked that version.
But Malhotra and colleagues found no evidence for that effect in 193 Finns who were free of mental illness, nor in 138 Finnish alcoholics.
There are several possibilities for that, Malhotra said. The gene variant was defined as containing seven repeats of a particular section of the gene, and this section itself comes in a number of variants. So maybe the crucial thing for an impact on personality is not just a seven-fold repeat, but rather the contents of the section being repeated.
Or maybe the seven-repeat section itself doesn’t influence novelty-seeking but is simply inherited along with the real genetic cause of the association in Israelis, but not in Finns, he said.
Also, because the evidence is statistical, scientists can’t yet discard the idea that the original findings were just a fluke.
Ebstein said he was disappointed by the new finding but added it’s not a surprise. The gene variant has only a weak effect on novelty-seeking and there could be at least five other genes that influence the same trait, he said. In that situation, it’s likely that a given gene may have an effect in one ethnic group but not another one because of differences in other genes and in cultural upbringing, he said.
