The clustering of longevity in families; the evidence that centenarians’ lifestyles are no healthier than those of the rest of us; and the fact that genes alone can be used to predict whether a person will live to be 100 or older; these have led to a new consensus. It’s now accepted that the one-third statistic doesn’t apply to super-agers. “In centenarians, it’s probably 80-20,” says Barzilai. That is: 80 percent genetics, 20 percent lifestyle. Exceptional longevity, it turns out, is all in the genes.