Gene: Fighting, Bullying and Violent

Source: Want a fight? Scientists say it’s all in your genes, 04-02-2007

SCIENTISTS have found an answer to one of the most intractable squabbles in family life – argumentative and disruptive children are born, not made.

A study by American scientists has found that antisocial traits such as being argumentative, bullying and lying, are often inherited. The new research challenges the scientific consensus that difficult children are the product of disruptive homes and are copying parents’ behaviour.

The implication of the research, conducted by the University of Virginia, is that children with “antisocial” genes would behave badly even if they had been adopted and brought up in a happy family.

The effect appears to pass down the generations. It means that couples who fight a lot may be driven by their genes and pass them on to their children, who tend to behave in the same way.

More from other source:

In a study of adult twins and their children, researchers found that genes, rather than parents’ own argumentative behavior, seemed key in the children’s odds of serious conduct problems — like bullying, skipping school and shoplifting.

The findings, published in the Journal Child Development, touch on the classic nature-versus-nurture question.

In the case of child behavior, research has linked parents’ marital conflicts to long-term, serious conduct problems in their children. However, it has been unclear whether that means that marital woes themselves cause the behavioral problems.

The new findings suggest it’s more a matter of genes. That is, parents who are naturally argumentative pass on these traits to their kids.

“Marital conflict doesn’t appear, in this study, to cause stable patterns of conduct disorder,” explained lead study author K. Paige Harden of the University of Virginia in Charlottesville.

“Rather, marital conflict is influenced by parents’ own characteristics — including their genes — and these genes are passed on to children,” she told Reuters Health.

Harden and her colleagues arrived at their conclusions by studying 1,045 adult twins and their children. Some of the twin pairs were identical, which means they shared all of their genes; the rest were fraternal, meaning they shared only some of their genes.

On similar note,

In 2002, Avshalom Caspi, Ph.D., of the Institute of Psychiatry in London and colleagues reported in the journal Science that a particular version of a gene plays a role in anti-social behavior. The gene in question was the monoamine oxidase A gene (MAO-A gene), located on the X chromosome. This gene helps people digest food containing amine groups such as serotonin and inactivates neurotransmitters such as dopamine.

Specifically, Caspi and his coworkers found that maltreated boys who had a particular variant of the MAO-A gene that produces low MAO-A activity were more likely to develop antisocial problems than were maltreated boys who had a version of the MAO-A gene that produces high MAO-A activity. In other words, it looked as though possessing the MAO-A gene version that leads to low MAO-A activity might interact with an adverse childhood to produce antisocial behavior.

The above finding has now been replicated by a group of researchers at Virginia Commonwealth University. The lead investigator was Debra Foley, Ph.D., an assistant professor of human genetics at Virginia Commonwealth University. Results appeared in the July Archives of General Psychiatry.

The MAO-A gene, in fact, appears to be the first gene strongly linked with either conduct disorder or antisocial behavior, Foley indicated to Psychiatric News. Or at least, she said, there are “none with major effects that has been independently replicated that I know of.”

The study included 514 white male twins from the community-based, longitudinal Virginia Twin Study for Adolescent Behavioral Development. The twins were 8 to 17 years old. Twins and their parents were interviewed at home by trained field workers at several different time points to learn whether the twins were exhibiting signs of conduct disorder and/or were being brought up in an adverse environment—that is, one of inconsistent discipline, parental neglect, or interparental violence. DNA samples were also taken from the twins at two different time points for analysis to see whether the twins contained a version of the MAO-A gene that produces low MAO-A activity in the body.

The researchers found that among the twins participating in the study, the prevalence of conduct disorder was 11 percent, the prevalence of a low-activity MAO-A gene was 29 percent, the prevalence of exposure to inconsistent parental discipline was 17 percent, the prevalence of exposure to parental neglect was 13 percent, and the prevalence of exposure to interparental violence was 3 percent.

The investigators found that inconsistent parental discipline, parental neglect, and exposure to interparental violence were independent risk factors for conduct disorder, but a low-activity MAO-A gene was not. However, a low-activity MAO-A gene was determined to be a risk factor for conduct disorder when combined with an adverse childhood environment.

The findings suggest “a relatively robust effect of MAO-A in combination with exposure to environmental adversity on risk for conduct disorder,” Foley and her team concluded in their study report. The results, they pointed out, “are also consistent with reports from adoption studies describing an increased risk for antisocial behavior in boys in association with an interaction between aggregate genetic effects and exposure to adversities within the adoptive family.”

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