Their study, which was funded by the National Institute of Aging, which is part of the National Institutes of Health, found that genetics are about 33 percent responsible for how we feel physically and about 36 percent responsible in determining our mental and emotional well-being. It was published in the November issue of Medical Care.
"Attitudes and perceptions have a genetic piece and an environmental piece," said James Romeis, Ph.D., professor of health services research at Saint Louis University School of Public Health and the principal investigator of the study.
"Health-related quality of life is our perception of health and how we believe disease and illness impacts our ability to function. It's much more influenced by genes than we thought."
The researchers looked at a total of 2,928 middle-age, middle-class, predominately white men who were on the Vietnam Era Twin Registry and interviewed them over the phone about their health.
They compared information they received from sets of identical twins (who have exactly the same genes) with fraternal twins (who share half their genes). The researchers asked about eight factors that measure health-related quality of life -- physical functioning, physical limitations, pain, general health, vitality, ability to function socially, emotional limitations and mental health.
"This isn't just an attitude. This is an attitude that is deeply rooted in their soul - not only their psychology but their biology," Romeis said. "The genetic influence is something we haven't recognized before and we have to give it more thought."
Romeis says he doubts that there is any one gene that predisposes men to feel healthy.
"However it is plausible that there are complex genetic relationships that affect how we feel about the quality of our health."
The findings may shed light on how people use health services, such as why some people are more likely to call the doctor about medical problems than others or why some don't follow prescribed medical treatments, he added.
They also help to explain why health promotion and prevention efforts, such as a new dietary pyramid and new recommendations for exercise, may not be enough to overcome the force of genetics to help people become healthier.
"Further research is warranted," Romeis said.
Saint Louis University School of Public Health is one of only 37 fully accredited schools of public health in the United States and the nation's only School of Public Health sponsored by a Jesuit university. It offers masters degrees (MPH, MHA and MS) and doctoral programs (Ph.D.) in six public health disciplines and joint degrees with the Doisy College of Health Sciences and Schools of Business, Law, Medicine and Social Service. It is home to seven nationally recognized research centers and laboratories with funding sources that include the National Institutes of Health, the Centers for Disease Control and Prevention, the Health Resources and Services Administration, the American Cancer Society, the Robert Wood Johnson Foundation and the World Health Organization.