After just under a year in space, astronaut Scott Kelly’s gene expression changed significantly and it’s different to his identical twin brother’s DNA. A new NASA statement suggests the physical and mental stresses of Scott Kelly’s year in orbit may have activated hundreds of “space genes” that altered the astronaut’s immune system, bone formation, eyesight and other bodily processes. While most of these genetic changes reverted to normal following Scott Kelly’s return to Earth, about 7 percent of the astronaut’s gene expression remained altered — and it may stay that way permanently.
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