By Barbara D’Amato
For nearly twenty years researchers have described a link between antisocial behavior and low activity on the MAO-A gene. A defect in this gene produces an excessive breakdown of the neurotransmitter serotonin, a substance that makes humans calm. The defect increases anger and produces an urge to react with aggression to fear or threat. [MAO-A has been called the “warrior gene”].
A Florida State University study on the tendency to join gangs, released this week, goes further. In young men, low activity on the MAO-A allele was associated with a greater tendency to violence, to use weapons, and to join gangs.
The National Longitudinal Study of Adolescent Health, which began in 1994 and therefore has been able to follow subjects for many years, surveyed 2,500 young males between 7th and 12th grade. The findings: Compared with males with a high-active gene, males with a MAO-A allele with low activity were twice as likely to join a gang, and more than four times as likely to use a weapon, even compared with other gang members, if those other gang members has a high-active gene.
A British study found that a combination of low-active MAO-A and a history of being abused produced males who committed four times as many robberies, rapes, and assaults.
Males who had the high-active MAO-A gene seemed to survive childhood abuse, having no more violent history than the average male. As Joshua Buckholtz at Vanderbilt University’s Brain Institute puts it, the genes “do an important job in loading the gun. But it’s the environment that pulls the trigger.”
In a way, this is encouraging. A study at the University of Georgia, published this May, found that five years of enrollment in a prevention program reduced binge drinking, drug use, and other antisocial behaviors to levels average in the general population.
These studies, though, give us all another big question for the blame game. Sure, when a young man has engaged in violent behavior repeatedly, he needs to be put where he can’t hurt anybody else. But what about the question of punishment?
Do we punish when there is genetic evidence of diminished restraint coupled with childhood abuse the child certainly never asked for?