By
msnbc.com contributor
updated 7/2/2007 8:14:44 AM ET 2007-07-02T12:14:44

Janet Thomas’ marriage had been on the rocks for years. When the constant conflict became unbearable, she moved out.

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But Thomas spent the next 10 months in counseling trying to patch things up because she worried that a divorce might hurt her three kids, then ages 6, 10 and 13.

“I’d read that kids did worse in school and some turned to violence,” Thomas, 45, remembers. “And to be honest, I was a little worried about depression and suicide attempts.”

In the end, the couple couldn’t work things out. And when one of Thomas’ kids, a teenager by then, attempted suicide a couple of years later, she feared that the divorce might have been to blame.

Numerous studies have found that growing up in a broken home increases a person’s risk of developing depression or having problems with anxiety later in life.

But a new report suggests that divorce isn’t at the root of the offspring's depression after all. In fact, the study, published in the July issue of the Journal of Child Psychology and Psychiatry, found that the cause of the divorce and the depression might be the same: shared genes.

“This study suggests that the increased risk of emotional problems in the offspring of divorced parents is due to genetic risk shared by parents and their offspring,” says the study’s lead author, Brian D’Onofrio, an assistant professor of psychology at Indiana University. “This is contrary to what a lot of people have assumed in sociology and psychology.”

Divorce not off the hook, however
That doesn’t mean divorce has no impact on children, D’Onofrio says. His research did find that divorce led to an increased risk of alcohol abuse in people who grew up in broken homes.

And, D’Onofrio says, one of his earlier studies found that certain problem behaviors, such as skipping school, getting into fights and stealing, could be traced to divorce.

The researchers teased out the contributions of genetics and divorce using a new twist on an old strategy — the twin study.

Twin studies are one approach to disentangling the contributions of genes and environment. Scientists compare identical twins — who are perfect genetic replicas of one another — to fraternal twins, who share smaller amounts of DNA.

If there is a genetic root to the trait being studied, then the identical twins will be more similar than the fraternal twins.

In a bit of a twist, D’Onofrio and his colleagues studied 4,800 children of twins. The average age of the offspring was 35 years, but the subjects ranged in age from 16 to 79.

The researchers first looked at children of fraternal twins and the results agreed with previous studies: The offspring of divorced twins were more likely to be depressed or to have problems with anxiety than their cousins whose parents stayed married.

But when D’Onofrio and his colleagues looked at the children of identical twins, they saw something surprising among the cousins. “It didn’t matter whether the parents got divorced or not,” D’Onofrio says. “The offspring had the same levels of depression and anxiety.”

This points a finger directly at genetics, D’Onofrio concludes. In other words, parents who are more likely to be unhappy in their marriages have children more prone to depression.

The new study is going to spark a lot of discussion, says Dr. David Fassler, a clinical professor of psychiatry at the University of Vermont, College of Medicine, who wasn’t involved with this study. “It challenges some of our assumptions about the effects of separation and divorce on children and adolescents,” he adds. “The results are intriguing, and likely to stimulate further research in this area.”

Divorce has been linked to a wide range of outcomes, says Tom O’Connor, an associate professor in the department of psychiatry at the University of Rochester Medical Center in New York.

Unhappy at home
One thing that’s not clear is whether those outcomes are caused by the divorce or by the bad family situation that led to the divorce, O’Connor explains.

Studies in which couples were followed prospectively — meaning that researchers started watching the families before divorce was being contemplated — found that problem behaviors in children started well before parents split.

So, for instance, the link between divorce and alcohol problems might be attributed to an unhappy family, rather than the eventual divorce.

All this means is that parents with troubled marriages need to be mindful of how they behave around their children, says Michael Goldberg, director of Child and Family Psychological Services in Norwood, Mass., and a psychology instructor at the Harvard Medical School.

If you want to make things easier on your kids, don’t fight in front of them, says Goldberg. One of the best predictors of how children will do after a divorce is the level of parental conflict, he adds.

Things were so bad in Janet Thomas’ home that the kids were relieved when their parents split up. “There was so much tension in the house,” she remembers. “Afterwards, my daughter said, ‘It’s better now. You can breathe around here.’”

And now, eight years after the divorce, Thomas’ children seem to have moved beyond their parents’ separation. “Two of them are in college and one is about to start high school,” she says. “They seem to be thriving.”

Linda Carroll is a health and science writer living in New Jersey. Her work has appeared in The New York Times, Newsday, Health magazine and SmartMoney.

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