GENETIC CHANGES DUE TO SPACE TRAVEL:

Accoriding to a study of NASA they found changes in gene expression and other biological markers in astronauts.Astronaut Scott Kelly who spent almost a year in space and his identical twin Mark who was here on land,measurements taken before,during and after Scott's mission show changes in gene expression,DNA methylation(modification of strand after its replication) and other biological markers that are likely to be attributable to his time in orbit.

From the length of twins' chromosomes to the microbiomies in their guts everyone(geneticist) reported that there are differences.

the challenge now is to differntiate between the the observed changes that how many are specific to the physical demands of space and how many of are from natural variations.

Since kelly twins are just two persons the result may not be generalisabe to everyone

CAUSE OF CHANGES:

The researchers  reported that changes in gene-expression signatures between the twins. Such changes happen in earthbound people all the time, associated with environmental shifts such as changes in diet and sleep habits.

NASA astronaut Scott Kelly (right) spent a year aboard the International Space Station without his twin brother, Mark, who is also an astronaut. Credit: Robert Markowitz NASA