Scott Kelly has a twin brother. Before the trip, they were the same height, but after a year, conducted in the microgravity environment of an astronaut has become of him above. Why? Because - as explained OUR - without "pressure" from the force of gravity is able to stretch the spine.
To the detriment of the astronaut, this effect is only temporary. It is not known, how long will it take to return to normal growth, but scientists say, it may even be a few months.