I guess this could have gone into the “Space” thread too:
Astronaut Scott Kelly has an identical twin (Mark) who is also an astronaut. Scott Kelly has spent over a calendar year in space while Mark Kelly has spent only(!) 54 days in space. NASA has begun doing some genetic testing on the two to see where their genes might have started to diverge. The idea is that since they are effectively clones and had very similar life-experiences and health, any divergence seen will likely be the result of their time spent in free-fall.
[quote]One of the differences was found in
the twin’s telomeres. If you picture a chromosome as an X-shaped unit of
DNA, telomeres are the caps on the end of each leg of the X. These act
as a buffer so that no important DNA is spilled from the chromosomes as
cells divide, though this causes the telomeres to shorten over time.
This process is linked to aging and much of the recent research around
telemores has focused on regulating their length as a way of slowing or
reversing our biological clocks, and even preventing cancer.
Studies into each of the brothers’ telomeres revealed that Scott’s grew to be
longer while he was in space, but returned to their normal length pretty
quickly once he returned to Earth. This is the opposite of what the
scientists expected to happen. They are now conducting separate research
into telomere length in ten other astronauts and hope that the results
may help them better understand this mysterious effect.[/quote]