A NASA study of twin brothers has offered new insights into the stress of space travel on the body — including genetic differences between Scott Kelly, the twin who spent nearly a year in space, and his brother Mark, who stayed on Earth. As twins with parallel career paths at NASA, the two men have almost identical genomes and similar life experiences. DNA methylation — a chemical marker in DNA that can affect gene expression — decreased in Scott Kelly during his time in space and increased in Mark over the same period. Scott Kelly gives himself a flu shot in zero gravity on Sept. 24, 2015. Gathering data from other astronautsMason's team also reported changes in gene-expression signatures between the twins.

Source: CBC News January 31, 2017 09:56 UTC