After a Year in Space, Astronaut Scott Kelly Is No Longer Genetically Identical to His Twin Brother

(via Mental Floss) After 342 consecutive days on the International Space Station from 2015 to 2016, astronaut Scott Kelly now holds the record for longest single space mission by an American. But his “One-Year” study with NASA was about more than breaking records: Its purpose was to show how prolonged time in orbit would effect Kelly’s genetic makeup compared to that of his identical twin brother on Earth. Now, it appears that Scott Kelly and his brother Mark are no longer genetically identical.