Adolescent depression and behavior problems are on the rise due to many factors, but parental depression is contributing to the increase in their children regardless of whether they are genetically related, say researchers from Penn State and Michigan State.
The work appears in the Cambridge University Press.
“We know from previous studies that genetic influences account for a substantial transmission of behaviors between parent and child. We wanted to explore the sources of this transmission by looking at their genetic relatedness,” said lead researcher Alex Burt, professor of clinical science at Michigan State.
A lot of genetic research focuses on relatedness of the children, their genetics, and what makes them alike, says member Jenae Neiderhiser, Social Science Research Institute cofunded faculty member and distinguished professor of psychology and human development and family studies at Penn State. “So many developmental studies are interested in parents just as a source of information for their child. Now more information on the parents themselves is becoming available and being used in studies of adoptive families, blended families, and other genetic research.”
The researchers looked at naturally occurring variations in genetic relatedness between parents and their adolescent children in the 720 families participating in the Nonshared Environment in Adolescent Development (NEAD) study, with over half of those families containing a child-rearing stepparent. The team focused on stepfathers because in almost all of the blended families in the study, mothers retained custody of their children.
Mothers, fathers, and children each answered questions to measure symptoms of depression, behaviors, and parent-child conflict. The researchers then examined the association between paternal depression symptoms and child behavioral symptoms in a series of models.
Burt and Neiderhiser, who have been collaborating on projects since the early 2000s, along with the rest of the research team found paternal depression was associated with adolescent depression and adolescent behavior problems regardless of whether the fathers and their children were genetically related.
“The results pointed squarely to the environmental transmission of depression and behaviors between fathers and children,” said Burt. “Additionally, we continued to see these associations in a subset of ‘blended’ families in which the father was biologically related to one participating child but not to the other, which was an important confirmation of our results. We also found that much of this effect appeared to be a function of parent-child conflict. These kinds of findings add to the evidence that parent–child conflict plays a role as an environmental predictor of adolescent behaviors.”
According to Neiderhiser, while the results were expected, they also thought the effects on children’s behavior and depression would be greater in parent-child pairs who were genetically related. “It would be great to do more studies on step and blended families. They tend to be an underutilized natural experiment we could learn more from to help us disentangle the impacts of environmental factors and genetics on families.”
Funding for this project was provided by the National Institute of Mental Health and the William T. Grant Foundation.