I’m not sure how they’re obtaining these numbers, but three studies cited claim that 25-35% of variance in longevity is can be attributed to genetic influences, leaving 65-75% to environmental effects.
A compelling example of the large impact of environment is that Seventh Day Adventists benefit from their otherwise nutty attempt to follow Leviticus by avoiding meat, tobacco, alcohol and sloth, obtaining a life expectancy of 88 years, versus 78 years for (presumably genetically very similar) average Americans. I have heard many times that Adventists practice healthy lifestyles, but this is the first time I’ve seen a number attached to their health outcomes (not that I’ve looked).
The article also seems to generally comport with economist Robert Fogel‘s research–environment early in life has long term health effects and those who achieve exceptional longevity tend to greatly delay or avoid aging related disease rather than fulfilling the stereotype of merely living longer, but in a miserable state. A healthy lifestyle may substantially increase your lifespan and simultaneously decrease the total amount of time you spend in a disabled state. What a deal.
For whatever it’s worth, the researchers at the NECS have a Living to 100 Life Expectancy Calculator. It expects me to live to 94.