I am so intrigued by this story of twin astronauts, born identical, that biologically are no longer identical.
Mark and Scott Kelly participated in a NASA study to look at how long-term space travel affects the human body. One spent a year in space, while the other stayed on earth as the control. They just found out that Scott's DNA is no longer identical to his brothers.
The "Twin Study" revealed that's gene within Scott's body had changed. Those dealing with bone development, oxygen, and immune systems where no longer exactly like his brother's genes. Space had mutated them into unique genes and changed their function. 7% of his genes did not return to normal, even after two years back on Earth. (CNN)
So is he a legit alien now? Scientist now have a better understanding of how exactly the human body is affected by space. Sadly, he still came back looking like the Gru from Despicable Me.