Does an Astronaut’s DNA Change in Space?? | #AskAbby | Season 2 | Episode 10 | The Mars Generation

Season 2, Episode 10 of The Space and Science Show #AskAbby series

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Does an Astronaut’s DNA Change in Space?

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In the 10th episode of #AskAbby Season Two, please join Astronaut Abby as she answers the question, “Does an astronaut’s DNA change in space?” In early 2018, NASA reported that astronaut Scott Kelly, after returning from a year in space, had 7% different DNA than his twin brother, Mark Kelly. So, did space really change his DNA? Find out by watching this episode of the #AskAbby Space and Science Show!

Includes answers to questions including: What are the effects of space on DNA? What exactly are the factors about space travel that could affect DNA? What is the difference between DNA and gene expression? What’s an example of DNA expression? What is mRNA? What would happen if 7% of your DNA really changed?  And much more! 

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In March of 2018, news broke out that during his year-long stint in space, Astronaut Scott Kelly’s DNA had changed. But does space really change your DNA?


Hi there! I’m Astronaut Abby, an aspiring astronaut with the goal to be the first person to walk on Mars! Welcome to Ask Abby, where I answer questions about space and science submitted by you, the viewer!

This episode, we’re going to be talking about the very popular and relatively recent news that being in space can change human DNA, based on the study done on NASA identical twin astronauts, Mark and Scott Kelly.

Several sources have reported that when Astronaut Scott Kelly returned from his year in space, his DNA had changed by 7% from that of his twin, Mark, who had stayed here on Earth.

Naturally, the internet went abuzz with this information – the idea that space could change your DNA seems to be straight out of science fiction – but is it really true?

Well… the short answer is no.

If 7% of your DNA changed, you wouldn’t even be human anymore. And since Scott Kelley still looks and acts like a living, breathing human, it’s pretty obvious that 7% of his DNA couldn’t have changed. Unless he’s a secret lizard person. Huh, that must be it.

What the sources got wrong is that it wasn’t 7% of Scott’s DNA that changed, it was 7% of how his DNA expressed itself that changed. But wait, what even is gene expression?

Gene expression is the activity of the DNA. So not what the DNA is, but rather what the DNA does. Scott Kelly’s DNA itself is the same, but what his DNA does is 7% different.

An example of a change in gene expression is that Scott’s DNA may produce more or less mRNA than it normally would. mRNA, for those of you who don’t know, is a messenger that tells proteins what to do. Kind of like parents.

But why does space change the expression of your DNA?

Seeing as this is such a recent discovery, research is still being done and we don’t concretely know. BUT one of the simplest answers is that space is a really stressful environment, and stress has been shown in the past to change the way that DNA expresses itself.

So it’s not some mystical, mysterious quality about space that’s causing astronauts’ DNA expression to change, but rather just the stress of living in really difficult situations. Kind of like finals. Probably why I seem like a different person then.

With limited room to move around, radiation, homesickness, detachment from Earth and humanity, constant pressure to perform, and your sleep cycle being thrown off from the lack of a proper night and day schedule, it’s understandable that astronauts are under a pretty significant amount of stress (and by stress we don’t just mean mental stress, but also stress on their physical bodies).

Fortunately though, once astronauts return to Earth and are no longer in those same stressful conditions, their DNA expression can change back to much closer to what it was before they went to space.

Not all of it changes back though. Scott Kelley’s DNA will never be 100% of what it was before he went into space. So going into space does have a small, but permanent effect on an astronaut’s DNA.

That’s all the time we have today for AskAbby. Thank you all so much for joining me for this segment of The Mars Generation’s Space and Science Show.

If you enjoyed it, and I hope that you did, please go ahead and click the “Thumbs Up” button to give us a like, and make sure to subscribe so that you see all of our super cool and interesting episodes that will be coming out in the future. And as always, if you’d like to ask me a question, and potentially see it answered here on AskAbby, you can do so by Tweeting it to me with the hashtag #AskAbby, or by submitting it at, which is linked below.

Until next time, farewell fellow travelers of spaceship Earth!

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