A genetically informed study of the intergenerational transmission of marital instability

The first study to examine genetics as a culprit in the higher-than-usual divorce rate among children of divorced parents found that the parents' divorce itself, not genes or even problems such as parental substance abuse or delinquency, played a key role in the failed unions.

Children of divorced parents are roughly twice as likely to see their relationships end in divorce compared to their peers from intact families.

Brian D'Onofrio, assistant professor in the Department of Psychological and Brain Sciences at Indiana University Bloomington, said that when a host of variables are taken into consideration, such as genetic risks and socioeconomic factors, the actual divorce still accounts for around 66 percent of the increased risk of divorce faced by children of divorced parents.

"This means the transmission is not due to psychological or substance abuse problems that are passed from parents to the offspring," he said. "It's something very unique about the separation of one's parents. The societal implications are very important because divorce is such a painful experience for both adults and children. This further suggests that interventions specifically targeted at the consequences of divorce are important for our society."

Many communities across the United States have formal and informal programs geared toward helping families cope with divorce. Some courts, for example, require parents to take classes that discuss the impact of divorce on children, D'Onofrio said.

D'Onofrio's findings appear in the August issue of Journal of Marriage and Family . Co-authors include Eric Turkheimer, Robert E. Emery and K. Paige Harden, professors at the University of Virginia; Wendy S. Slutske, professor at the University of Missouri; Andrew C. Heath and Pamela A.F. Madden, professors at Washington University School of Medicine; and Nicholas G. Martin, professor at the Queensland Institute of Medical Research.

For a copy of the study, "A genetically informed study of the intergenerational transmission of marital instability," contact Sean Wagner at [email protected].

The researchers used a novel research design--the study of the children of twins--to test assumptions in traditional family studies. The design helps investigate the role that genetic and environmental factors play when studying how parents influence their offspring. Scientists are able to take into consideration a host of genetic and environmental variables, both those already measured by other researchers and those yet unmeasured, because the offspring of twins have more genetic risk and environmental factors in common than unrelated people.

D'Onofrio said the findings are important in light of the national debate about the meaning of marriage.

"This study, because it tested a lot of the assumptions of previous research, further supports the conclusion that if we reduce parental divorce or its impact on children, that we can reduce the number of divorces in our society in future generations."

D'Onofrio's study tests assumptions and rules out potential causes, but it does not identify why children of divorced parents experience the increased risk. Previous studies, he said, point to a lack of commitment among these offspring. But he cautioned that not all children of divorced parents should be painted with the same brush.

The research is supported by the National Institute of Mental Health, the W. T. Grant Foundation, the National Institute on Alcohol Abuse and Alcoholism, and the National Alliance for Research on Schizophrenia and Depression.

D'Onofrio is the co-author of a study appearing in the July issue of the Archives of General Psychiatry . The article, "Intergenerational transmission of childhood conduct problems," explores why parents with a history of conduct problems are more likely to have children with more conduct problems. The study can be found at http://pubs.ama-assn.org/media/ or by contacting 312-464-JAMA or [email protected].

D'Onofrio also is co-author of "A children of twins study of parental divorce and offspring psychopathology," appearing in the Journal of Child Psychology and Psychiatry this month. For a copy of this article, contact Wagner at [email protected]. Both articles study the children of twins.