Astronaut Scott Kelly spent a year in space and his DNA changed 7 percent — no longer matching that of his identical twin, Mark

By Julie Mazziotta
March 15, 2018 10:15 AM
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Scott, 54, returned in March 2016 from a year aboard the International Space Station — but 7 percent of his genes had changed. In the two years since, they have not returned to normal, NASA says.

Scott’s 340-day stay was longer than NASA’s typical six-month deployments to space, and while it is known that a person’s genes change away from Earth, they did not expect his genes to stay altered.

NASA says the 7 percent DNA changes, which they call “space genes,” bring up “possible longer term changes in genes related to his immune system, DNA repair, bone formation networks, hypoxia, and hypercapnia.”

Credit: KIRILL KUDRYAVTSEV/AFP/Getty

Scott Kelly

As identical twins, Scott and Mark, who is also a former astronaut, were purposefully studied before, during and after Scott’s mission to research the changes that occur in space.

Credit: Steve Jennings/WireImage

(L-R) Scott and Mark Kelly

Scott tweeted on Saturday that he wasn’t aware of his “space genes” until reading about it in a Newsweek article.

“What? My DNA changed by 7%! Who knew? I just learned about it in this article,” he tweeted, joking: “This could be good news! I no longer have to call @ShuttleCDRKelly my identical twin brother anymore.”

NASA says these findings will aide in their preparations for a three-year mission to Mars, as they figure out the body changes that will occur when humans spend over 1,000 days in space.