WASHINGTON, D.C. — Identical NASA twin astronauts Scott and Mark Kelly no longer share the same DNA after the former spent a year in space.<br /><br />According to NASA, scientists compared the twins' DNA and RNA via whole-genome sequencing. They found that 7% of Scott's DNA had changed into so-called space-genes.<br />His immune system, bone formation and eyesight all went under changes, reported Live Science.<br /><br />Telomeres, caps on chromosomes, typically shorten as a person ages. Kelly's lengthened, according to NASA, but returned to normal two days after he returned to Earth.
