A NASA twins study made waves following the initial report published in February stating the 7 percent difference between Mark and Scott Kelly’s DNA. Following reports suggesting outlandish conclusions from Kelly’s space genes, the agency decided to clarify the implications of the initial findings based on the twin astronauts.
How Scott Kelly’s DNA Changed
NASA updated their preliminary findings based on the twins study to reflect these changes.
“Mark and Scott Kelly are still identical twins; Scott’s DNA did not fundamentally change. What researchers did observe are changes in gene expression, which is how your body reacts to your environment. This likely is within the range for humans under stress, such as mountain climbing or SCUBA diving.”
Some outlets claimed Scott is no longer an identical twin with Mark, the control subject for the NASA study. This stems from the news that 7 percent of Scott Kelly’s genes did not return to normal following his arrival from a 340-day stay on the International Space Station. Scott’s “space genes” do not exist, and NASA clarified just how his DNA changed.
In NASA’s update, they emphasized that Scott Kelly’s fundamental DNA was not the thing that changed; it was how it was expressed.
As noted by the Washington Post, Scott Kelly has the same DNA before and after he left for space. However, the thing that changed was in the transcription and translation of his DNA into a functional product. The study of this shift is known as epigenetics.
Epigenetics is one of the most popular fields of science. This is also the reason why identical twins are not the same. Some traits inherited from parents that don’t seem to be genetic can also be the result of epigenetics.
As noted by The Guardian, outside stimulus can cause epigenetic modifications. Lifestyle factors are known for causing some of these changes.
BPA, an additive in plastic which is a carcinogenic substance, has been linked to epigenetic modification. Exercise and childhood trauma may also cause changes. As explained by NASA, the epigenetic changes affecting 7 percent of Scott Kelly’s DNA happened due to his exposure to a new environment. Oxygen deprivation, low gravity, diet changes, and inflammation are all contributory factors for his epigenetic modification.
As reported by Weill Cornell Medicine’s Chris Mason who looked into the epigenetic changes in Kelly’s DNA, five biological pathways changed including those related to bone formation, oxygen deprivation, and DNA repair. These molecular changes are what makes up “space genes” or the cellular functions affected by the time a person spends outside the Earth.
NASA also clarified that Scott Kelly’s epigenetic changes which are pegged at 7 percent are minimal, and the same level of change as what would be expected from scuba divers or any other human under stress.