Astronaut Scott Kelly still has an identical twin!
Scott Kelly left an identical twin behind when he took off from the Earth and stayed in the space station for a full year.
This was revealed in preliminary results from the space agency's twins study, according to CNN. DNA changes weren't the only differences in Scott's body, either. Kelly still has the same DNA, yet now has a change to the way some of the DNA expresses itself.
The findings are part of the Twins Study, which seeks to explore the physical and psychological effects of space travel. That months-old update appears to have fueled this week's rash of inaccurate stories; Kelly Humphries, a NASA spokesman, said there were no new developments this week. What changed was the transcription and translation of some of S. Kelly's genes.
Colorado State University's Susan Bailey, who leads one of the research group, said Kelly's exercise routine and diet most likely caused the chromosomal bungee.
Derrick Pitts, chief astronomer and planetarium director at the Franklin Institute, told CBS News that understanding these factors becomes especially important when considering the potential for longer-term human space exploration and the health effects that could have on the body. Researchers discovered that while 93 percent of Scott Kelly's genes returned to normal after landing, the remaining 7 percent did not. First, there was a significant increase in average length while he was in space, and then there was a decrease in length within about 48 hours of his landing on Earth that stabilized to almost preflight levels. The changed genes were connected to his immune system, DNA fix, bone formation networks, hypoxia and hypercapnia.
The findings showed that after returning to Earth, Scott started the process of readapting to Earth's gravity.
"The NASA result everyone is freaking out about actually measured Scott Kelly's expression levels, and it found that - not surprisingly - spaceflight affects how much expressing certain genes do, particularly those involved in immune function, DNA fix pathways, and bone growth", Nadia Drake wrote in National Geographic. Indeed, if seven percent of his DNA changed, he would literally be a different species.
Mason's team also saw changes in the length of Kelly's telomeres, caps at the end of chromosomes that are considered a marker of biological aging. Kelly's one-year on the ISS is a good precursor for a three-year mission NASA hopes to soon launch to Mars. Not only did his time in space give astronauts a new record, but it gave NASA a flawless opportunity to understand how the human body reacts to almost a year in space. NASA describes gene expression as "how your body reacts to your environment", and a huge variety of everyday factors - from the amount of exercise a person gets, to the type of diet they eat, to which drugs or toxins they're exposed to - can have an impact.