THURSDAY, Jan. 15, 2015 (HealthDay News) -- Environment plays a larger role than genes in shaping people's immune systems, a new study suggests.
Researchers compared 78 pairs of identical twins -- who are nearly genetically the same -- and 27 pairs of nonidentical twins, who have about 50 percent of their genes in common.
Three-quarters of the immune system differences between the twins were due to environmental influences such as previous exposure to microbes or toxins, vaccinations, diet and dental hygiene.
Among identical twins, environmental effects on the immune system were stronger among those 60 and older than among those younger than 20, the Stanford University School of Medicine researchers found.
The study was published Jan. 15 in the journal Cell.
"Nonheritable influences, particularly microbes, seem to play a huge role in driving immune variation," senior study author Mark Davis, a professor of microbiology and immunology and director of Stanford's Institute for Immunity, Transplantation and Infection, said in a university news release.
"At least for the first 20 or so years of your life, when your immune system is maturing, this amazing system appears able to adapt to wildly different environmental conditions. A healthy human immune system continually adapts to its encounters with hostile pathogens, friendly gut microbes, nutritional components and more, overshadowing the influences of most heritable factors," he explained.
The U.S. National Institute of Allergy and Infectious Diseases has more about the immune system.
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