Genes May Play Role in Turning Teens into Criminals
Researchers at the University of North Carolina reported Monday that genes may play a role in young men who grow up in tough neighborhoods or with disadvantaged families and later become violent criminals.
The scientists have identified three genes they believe play a role. One, called MAOA, played a particularly strong role, and had been shown in previous research to affect antisocial behavior. The researchers called the gene “disturbingly common”.
Sociology professor Guang Guo, who led the study, said those with a particular variation of the MAOA gene known as 2R were extremely prone to criminal and delinquent behavior.
“I don’t want to say it is a crime gene, but 1 percent of people have it and scored very high in violence and delinquency,” Guo told Reuters during a telephone interview.
Guo and his team studied only boys, and used data obtained from the National Longitudinal Study of Adolescent Health. The data provided a nationally representative sample of about 20,000 adolescents in grades 7 to 12. The young men involved in the study were routinely interviewed in person, with some providing blood samples.
Guo’s team then developed a “serious delinquency scale” based on some of the questions the participants had answered.
“Nonviolent delinquency includes stealing amounts larger or smaller than $50, breaking and entering, and selling drugs,” the team wrote in a report about the study.
“Violent delinquency includes serious physical fighting that resulted in injuries needing medical treatment, use of weapons to get something from someone, involvement in physical fighting between groups, shooting or stabbing someone, deliberately damaging property, and pulling a knife or gun on someone.”
Specifically, they found specific variations in three genes associated with bad behavior: the monoamine oxidase A (MAOA) gene, the dopamine transporter 1 (DAT1) gene and the dopamine D2 receptor (DRD2) gene. However, the bad behavior only occurred when the boys suffered from other stresses, such as failing school, family issues and low popularity.
MAOA regulates several neurotransmitters such as dopamine, serotonin and norepinephrine, which play an important role in aggression, emotion and cognition.
The links were very specific, the researchers said.
In fact, the study showed that the effect of repeating one school grade depended on whether an adolescent had a certain MAOA mutation called a 2 repeat. In addition, a certain DRD2 mutation seemed to set off a boy if he did not have regular meals with his family.
“But if people with the same gene have a parent who has regular meals with them, then the risk is gone,” Guo said.
“Having a family meal is probably a proxy for parental involvement,” Guo explained.
“It suggests that parenting is very important.”
Young people at risk might benefit from having surrogates of if their parents are unavailable, Guo said.
“These results, which are among the first that link molecular genetic variants to delinquency, significantly expand our understanding of delinquent and violent behavior, and they highlight the need to simultaneously consider their social and genetic origins,” the researchers wrote.
Guo said it was premature to begin considering whether drugs might be developed to protect such adolescents. He was also unclear if criminals might someday use a “genetic defense” in court.
“In some courts (the judge might) think they maybe will commit the same crime again and again, and this would make the court less willing to let them out,” he said.
The research was published in August issue of the American Sociological Review.
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