No, Scott Kelly's Year in Space Didn't Mutate His DNA

Scores of stories reporting that Kelly’s DNA is substantially different now are missing some basic facts about how biology works.

If you believe recent news, NASA astronaut Scott Kelly went to space, spent a year there, and came back with substantial changes to his DNA. Some outlets are even reporting that a whopping seven percent of Kelly’s genes—segments of DNA that code for various proteins—are “abnormal” post-spaceflight.

Unfortunately, even Kelly appears to be surprised by the news.

“What? My DNA changed by 7%! Who knew? I just learned about it in this article. This could be good news! I no longer have to call [Mark Kelly] my identical twin brother anymore,” Scott Kelly tweeted.

Well, and we hate to spoil the fun, but no. The story Kelly is referring to, and many more, misrepresent the results of a

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