A new study has found that adolescents from families with two biological parents enjoy significantly better physical health than adolescents from single-parent families, families with step-parents and families with cohabitating parents.

The relationship between family structure and health has become a pressing concern because of the changing nature of families. More than half of American children now spend a part of their childhood in single-parent families. A third of them live at some point with a step parent.

But despite great interest in how family type affects mental health, researchers have largely overlooked physical health. “A lot of research has found that mental health and physical health are very closely connected,” says Callie Langton, a policy analyst and researcher at the California Academy of Family Physicians. “We thought, ‘Okay, we know that family structure can affect mental health. We haven’t really looked at how it affects physical health.’” Langton and Lawrence Berger of the University of Wisconsin are the authors of “Family Structure and Adolescent Physical Health, Behavior and Emotional Well- Being” in the September 2011 issue of Social Service Review.

Langton and Berger used the Panel Study of Income Dynamics, a longitudinal study of 4,800 American families that measures characteristics such as unemployment, income and family composition. In addition to looking at physical health, their research was distinctive in two more ways. First, it included father-only families as a distinct type. (Langston and Berger found that the health effects of living in a father-only family were about the same for adolescents as living in a mother-only family.) 

Second, it looked at how family transitions affect adolescents. The data here were more meager and the findings less conclusive. But the study suggested that transitions from two-biological- parent families to single-parent families were harmful to adolescent physical health. Although variation across family types was not large—as little as a few percentage points on some measures—Langton says any variation is “very important” because adolescents are typically in excellent health. “It does make you stop and think because it really is a healthy population,” she says.

The study’s findings add to a growing body of research showing that children from two biological parent families do better than children from other family types, especially single parent families, enjoying such advantages as greater wealth, higher-quality parenting, closer emotional ties and fewer stressful events. The study did not reveal the causes of these differences. However, Langton and Berger offer that poorer physical health could have to do with greater stress or fewer opportunities to access preventative health care.

Langton, Callie E., and Lawrence M. Berger. 2011. “Family Structure and Adolescent Physical Health, Behavior and Emotional Well-Being.” Social Service Review 85 (3): 323-57.