Interesting study of what happens to human genetics when in space

Two identical twins, Scott and Mark Kelly, with Scott being an astronaut, took part in an important volunteer study. Scott lived in space for one year, and then their genetic expression were compared before, during and after the space time. About 7% of Scott's genes were altered. Check out this summary article - this is research that is absolutely vital before sending people to Mars for multiple years at a time. Zero gravity, radiation, environmental changes that can affect genetics, and more are to be studied.