If a flurry of news coverage is to be believed, a year in space can really wreak havoc on your DNA.
According to some press reports this week, NASA astronaut Scott Kelly’s DNA changed by 7 percent because of the year he spent living above the planet on the International Space Station. Kelly himself even tweeted about the idea that he’s no longer identical twins with his brother and fellow astronaut Mark Kelly.
But that’s not the full story.
Kelly’s base DNA didn’t actually change by 7 percent during his time in space.
His gene expression — the transcribing and translation of genes, not the genes themselves — was what actually changed during his year on the Space Station.