"The idea in some circles has been that if you sequence someone's genome, you can tell what diseases they're going to have 50 years later," said Mark Davis from Stanford University's Institute for Immunity, Transplantation and Infection.
But while genomic variation clearly plays a key role in some diseases, he said, the immune system has to be tremendously adaptable in order to cope with unpredictable episodes of infection, injury and tumor formation.
"When you examine people's immune systems, you often find tremendous differences between them. So we wondered whether this reflects underlying genetic differences or something else," said Davis, senior author of the study.
"But what we found was that in most cases, including the reaction to a standard influenza vaccine and other types of immune responsiveness, there is little or no genetic influence at work, and most likely the environment and your exposure to innumerable microbes is the major driver," Davis said.
To determine nature's and nurture's relative contributions, Davis and his colleagues turned to a century-old method of teasing apart environmental and hereditary influences.
They compared pairs of monozygotic twins, best known as "identical," and of dizygotic, or fraternal, twins.
By Ruchi Singh
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