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Scientists Discover Gene Linked To Aggressive Behavior in Humans

By Sheryl Stolberg
Los Angeles Times

More than three decades ago, a Dutch schoolteacher, troubled by a pattern of violence among his male relations, traced the pattern's origin to a couple who married in 1780. He concluded his kin must be suffering from an inherited mental disability. Pretending to be a dispassionate outsider, he then wrote up his notes under the title "A Curious Case."

The teacher has long since died. But Friday, his "curious case" earns a page in the annals of science, as a team of researchers from the Netherlands and the United States report that some men in his family harbor a mutant gene that predisposes them to aggressive behavior.

The discovery of what has been dubbed the "aggression gene" marks the first time a specific genetic defect has ever been linked to violent tendencies in humans. It adds to a growing -- and hotly debated -- body of evidence that indicates biological factors, as well as social and environmental causes, contribute to violent behavior.

The researchers found that the over-aggressive men had abnormal genes for a brain chemical that assists in coping with stress. But experts caution that their study, published in today's issue of the journal Science, is limited and cannot be applied to the general population, or used to explain the high rate of violence in the United States.

The study could be as controversial as it is dramatic. Research into the link between biology and crime has come under fire in recent months from those who fear such studies could be used to discriminate against racial minorities. Last year, the National Institutes of Health canceled a conference on the topic, and just last week black activists in Los Angeles protested a similar academic meeting.

Sensitive to these complaints, the Dutch and American scientists stress that the flawed gene, while important, is probably not the sole reason for the family's history of what they call "aggressive outbursts" -- which include a rape that occurred 50 years ago, two arsons and an incident in which one man tried to run over his boss with a car after getting a negative performance evaluation.

"I think this is the most convincing evidence for a biological factor so far," said Dr. Han G. Brunner, the Dutch geneticist who headed the study. "But our study does not give you an idea of how important biological factors are in aggression as a whole."

He noted that while one man in the study continues to have repeated outbursts, his brother -- who also has the genetic abnormality -- has not had one for many years, which suggests social factors and environment also play a role. "There is not a very simple cause-and-effect relationship here."

Others experts are equally reserved in their assessment of the work. "We're still unsure as to what it all means," said Gregory Carey, a University of Colorado psychologist who last year published a review of all scientific studies that have attempted to link crime to genetics. "We are not certain at all the extent of which this gene is present in the general population."