Heritability of intrinsic human life span is about 50%

A new study in Science just dropped a bomb: once you remove “extrinsic” deaths like accidents and infections, human lifespan looks about 50% genetic. The researchers mined century-old Scandinavian twin records—including twins raised together and apart—and say past low estimates were muddied by random bad luck. Cue the internet cage match: half the crowd cheers that longevity finally joins other traits in the “yep, genes matter” club, while the rest declares, “not so fast—your habits still count.” Numbers nerd Enginerrrd even ran back-of-the-envelope math: life expectancy varies roughly 12 to 15 years, and lifestyle might still swing 6 to 7.5 years. Translation: you can’t out-run your DNA, but you can jog around it.

Then the skepticism brigade arrives. emp17344 argues twin-based heritability is inflated and drops a spicy link. moi2388 worries the study overestimates genetics by lumping in shared childhood environments. Meanwhile logicallee tosses a tangential brain paper for flavor, and the thread devolves into meme territory: “eat your veggies, but also pick better parents.” Anecdotes roll in, like JoeAltmaier’s family roulette—grandparents at 97 and 81—fueling the “longevity lottery” joke. Verdict from the comments: genes set the table, but you still choose some of the menu. For now, debate rages.