Environmental Factors, Lifestyle Choices Have Greater Impact On Health Than Genes, Study Finds

Nature versus nurture: Scientists are gathering more evidence on which has more of an impact on human well-being amid the aging process.

While both environmental exposures and genetics are known to play important roles in shaping human aging, living conditions and lifestyle choices impact human health much more than genetics, according to a new study published Wednesday in Nature Medicine.

Researchers from Oxford Population Health used data from nearly 500,000 participants in the U.K. to assess the influence of 164 environmental factors and genetic risk scores for 22 age-related diseases and premature death, according to the paper.

The data showed that environmental factors accounted for 17% of the variation in risk of death, compared to less than 2% explained by genetic predisposition.

Smoking, socioeconomic status, physical activity and living conditions had the most impact on mortality and biological aging, the study found.

Smoking was associated with 21 diseases; socioeconomic factors -- such as household income, home ownership and employment status -- were associated with 19 diseases; and physical activity was associated with 17 diseases.

Group of women warming up and stretching on the floor during yoga class.

In addition, early life exposures were shown to influence aging and risk of premature death decades down the line. Factors such as body weight at 10 years old and maternal smoking around birth were shown to have an impact 30 to 80 years later.

Environmental exposures also had a greater impact on chronic lung, heart and liver disease, which are the leading causes of disability and death globally. Genetic risk had a greater impact for dementia and breast cancer, according to the researchers.

While many of the individual exposures played a small part in premature death, the combined effect of multiple exposures over the life course explained a large proportion of premature mortality variation, the researchers said.

However, 23 of the factors were identified as modifiable.

"'Our research demonstrates the profound health impact of exposures that can be changed either by individuals or through policies to improve socioeconomic conditions, reduce smoking, or promote physical activity," said Cornelia van Duijn, a professor of epidemiology at Oxford Population Health and senior author of the study.

Close up of male hand with cigarette.

The paper also detailed a new method of measure called the "aging clock," which monitors how rapidly people are aging based on blood protein levels. The new measure allowed researchers to link environmental exposures that predict early mortality with biological aging.

The approach allowed for "the most comprehensive overview to date of the environmental and lifestyle factors driving aging and premature death," said Austin Argentieri, lead author of the study research fellow at Massachusetts General Hospital.

Questions remain related to diet, lifestyle, exposure to new pathogens -- such as bird flu and COVID-19 -- chemicals like pesticides and plastics and the impact of environmental and genetic factors in different populations remain, the researchers said.

The study highlights the need for integral studies to improve the health of aging populations by identifying key combinations of environmental factors that address simultaneously the risk of premature death and many common age-related diseases, the researchers said.

"In an ever-changing environment, it is critical that we combine these techniques with novel advances in smart technology to monitor lifestyle and environment, as well as with biological data, to understand the impact of the environment over time," Argentieri said.

Jessica Yang, DO, a family medicine resident at Main Line Health Bryn Mawr Hospital and a member of the ABC News Medical Unit, contributed to this report.