After a ground-breaking space flight, an identical twin has slightly different genes from his brother.
NASA just released preliminary findings from its Twin Study. They show that after spending almost a year in space, astronaut Scott Kelly's DNA is now different than his twin brother's.
NASA recently released preliminary findings from its Twin Study involving astronauts Scott Kelly and Mark Kelly. Researchers now know that 93% of Scott's genes returned to normal after spending almost a year in space. However, the remaining 7% point to possible longer term changes in his genes.