If spending time with your family over the holidays stresses you out, you may not want to read any further.

Family ties have a stronger health impact than marital or partner relationships.

A new study conducted by a team including a University of Tennessee researcher suggests that strained relationships with parents, siblings or your own adult children not only make you feel bad emotionally — they can actually make you sick.

“We were really quite surprised,” said Patricia Roberson, an assistant professor in UT’s College of Nursing. She conducted the study with Sarah Woods, from the University of Texas Southwestern Medical Center, and Jacob Priest, from the University of Iowa. It was published in the Journal of Family Psychology.

The surprise was how much stronger the health effects are from negative family relationships than from negative relationships with a spouse or intimate partner. 

“A lot of research tends to just blanketly say marital relationships are the most important relationships in people’s adult lives,” Roberson said. “But when you delve into that, there’s no real empirical evidence for it.”

That’s why she and her colleagues decided to compare the two. They used data from a huge ongoing longitudinal study of middle-aged Americans, the Midlife Development in the U.S. (MIDUS) survey. Originated by the MacArthur Foundation and now carried on by researchers at the University of Wisconsin, the study tracked 2,802 middle-aged adults from 1995 to 2014, asking them a range of health and emotional/psychological questions.

Roberson’s team focused on sets of questions about “strain” and “support” from both intimate partners and family members. Questions for both included:

• How often do they make too many demands on you?
• How often do they criticize you?
• How often do they let you down when you are counting on them?
• How much do they really care about you?
• How much do they understand the way you feel about things?
• How much can you rely on them for help if you have a serious problem?

The researchers correlated the responses to those questions with self-reported physical health from the same respondents.

According to the study — which you can read here — illness (referred to clinically as “morbidity”) and chronic health conditions were higher for people with more strained family relationships. The correlation was much stronger than for strained partner relationships, where there was little demonstrable effect on later health.

“We found a robust impact of family emotional climate on both morbidity and health appraisal over the 20-year span of midlife,” the researchers write. “Specifically, greater family strain was associated with a greater number of chronic conditions, and worse health appraisal, 10 years later.”

Roberson said that in retrospect the findings make sense. Bad relationships with parents or siblings can affect people psychologically or emotionally even years after the fact.

“If you think about it, these are relationships that are much longer in duration than our marital relationships,” Roberson said. “These are relationships that you potentially grew up in.”

Roberson has done a lot of research with Woods and Priest, and the three have a podcast called Attached, where they talk about relationships, health and pop culture. They devoted one episode last month to their MIDUS study. 

Woods, who was first author on the study, said in the podcast, "Unhealthy relationships with parents and siblings and adult children and extended family, if we leave those unattended to, may have serious ramifications for your physical health throughout adulthood."

The mechanisms that translate emotional strain into physical illness most likely have to do with the well-established negative impacts of stress on the body. 

But there’s good news in the study, too. Supportive relationships with family members are correlated with better physical health. Roberson said even just one positive relationship with a family member can help offset the effects of negative relations. Among other things, people are more likely to discuss their health conditions with supportive family members, making it more likely that problems will be addressed.

The data is not detailed enough to separate out whether particular relationships have more impact than others — mothers vs. fathers, sisters vs. brothers, etc. But Roberson said people come from so many different family arrangements that it would be hard to isolate those effects. 

“In the end,” she said, “positivity is positivity, and negativity is negativity.”

CORRECTION: The spelling of Sarah Woods' last name has been corrected in some references.