Astronaut now has different DNA to his identical twin brother, and here is why

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Spending time in space permanently changes your genes, a shock new Nasa study has revealed.

Astronaut Scott Kelly now has different DNA to his identical twin brother after spending just a year in space, scientists found.

Nasa said the groundbreaking study is an important step in its preparations for a three-year mission to Mars in the 2030s.

After 340 days aboard the International Space Station, American astronaut Scott Kelly returned to Earth in March 2016.

Nasa has since undertaken an array of tests to study the effects the mission had on Kelly’s body using his identical twin Mark, who remained on Earth, as a control subject.

The Kelly brothers have nearly identical genomes, allowing for an unprecedented look at the physical effects of long-term spaceflight.

Blood and other biological samples were collected from the pair before, during, and after Kelly’s mission.

Nasa found that while 93 per cent of Kelly’s genes returned to normal shortly after returning home, seven per cent were permanently altered.

These long-term changes hit genes related to the immune system, DNA repair, bone formation and the ways his tissues take up oxygen and carbon dioxide.

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