Researchers from the University of California-Davis and the US Centres for Disease Control and Prevention found the link from harsh parenting to physical health is buffered by a warm and nurturing coparent.
However, when they measured the effect on body mass index (BMI), the health risk of harsh parenting increased as warmth from the other parent increased.
"Harshness leads to problems with physical health, and no matter how hard a spouse tries they may not be able to erase those effects," said lead author Thomas Schofield, an assistant professor at Iowa State University.
Researchers videotaped the interactions of 451 two-parent families to assess parenting behaviour.
Harsh parenting was defined as parents who reject, coerce, are physically aggressive and are self-centred.
No parent in this sample was observed hitting their adolescent, but there were other signs of physical aggression, such as pinching and pushing, researchers said.
Harsh parenting creates a chronic stressful environment that children can be exposed to for nearly two decades, said Schofield.
Other research shows there are negative biological responses - chronic release of hormones, inflammation and lower cardiovascular reactivity - that can result from chronic stress.
Researchers point out that the differences in physical health and BMI were not evident at the beginning of adolescence, which suggests that the negative health effects were not preexisting. The effects persisted into young adulthood after many had moved out of their parents' homes.
Most parents want what is best for their child and may not recognise or think their behaviour is overly harsh. Their parenting skills often reflect how they were raised, Schofield said.
More research is needed to fully understand what is happening within families to better explain the results for BMI, Schofield said.
He also points out that the higher BMI levels in young adulthood were not considered obese or dangerously overweight.
The study was published in the journal Social Science and Medicine.
