“Scott’s telomeres (endcaps of chromosomes that shorten as one ages) actually became significantly longer in space,” NASA researchers wrote in a statement. The space agency added that Kelly had hundreds of “space genes” activated by the year-long flight which reportedly altered the astronaut’s “immune system, DNA repair, bone formation networks, hypoxia, and hypercapnia.” While Scott Kelly’s height and 93 percent of his DNA returned to normal after returning to Earth, NASA confirmed that seven percent of his genes have remained changed and may stay that way. “This is thought to be from the stresses of space travel, which can cause...