In one of the most comprehensive analyses of immune function performed to date, researchers analyzed blood samples from 105 sets of healthy twins. They measured immune cell populations and their chemical messengers—204 parameters in all—before and after participants received a flu shot. Differences in three fourths of these parameters depended less on genetics than on environmental factors, such as diet and prior infections. Genetics had almost no effect on how well individuals responded to the flu vaccine, judged by antibodies produced against the injected material. And among identical twin siblings, who have the same genome, immune system features differed more strikingly within older twin pairs than in younger sets. The findings, published January 15 in Cell, argue that life habits and experiences shape our body’s defenses more than the DNA passed down from our parents.
Your Immune System Is Made, Not Born