NASA’s Twins Study sent astronaut Scott Kelly to ISS for a year, while his identical twin Mark stayed on Earth. They found Scott’s telomeres grew in length, his genes expressed themselves differently, his carotid artery walls grew thicker, and more.

NASA’s Twins Study sent one identical twin to space for a year, while the other stayed on Earth. Ten separate research projects then tracked how each twin changed.

About Robert Zinn

Robert Zinn, M.D., Ph.D. is a medical doctor, physician, and web entrepreneur, who, for over 15 years was employed by academic and research institutions and focused his clinical practices on very specialized patient populations, such as those with rare genetic diseases or rare cancers. He shares his knowledge through his website,

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