NEW YORK (WABC) -- You would expect a trip to space to be transformative, but NASA says it can lead to permanent DNA changes.
The space agency studied the DNA of twin astronauts Scott and Mark Kelly.
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Scott spent a year on the International Space Station while Mark remained on Earth.
Now two years later, NASA says 7 percent of Scott's DNA has changed, meaning the brothers are no longer identical.
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Read more from the NASA study.
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