# Austronaut genetics
**URL:** https://boards.straightdope.com/t/austronaut-genetics/507993
**Category:** Factual Questions
**Created:** [August 28, 2009, 2:50am UTC](https://boards.straightdope.com/t/austronaut-genetics/507993 "2009-08-28T02:50:51Z")
**Posts on this page:** 20
**Page:** 1
### Author:  [@wierdaaron](https://boards.straightdope.com/u/wierdaaron)
#### Post date: [August 28, 2009, 2:50am UTC](https://boards.straightdope.com/t/austronaut-genetics/507993/1 "2009-08-28T02:50:51Z")
Unless I am wrong, the major (if not only) thing that causes our DNA to change over time is cosmic and solar radiation. Cosmic rays assault and change our DNA slightly every moment, which is why 2 people can never produce the same offspring on two separate occasions (this can be evidenced by my aunt and her 13 kids).
Here on earth, we’re protected from most of the cosmic radiation out there by our magnificent magnetic field. The skuttlebut is, though, that when you leave earth you’re no longer subject to that aura of protection. I’ve heard that an astronaut on a space walk (like, say, repairing Hubble) receives something like 1,000 times the cosmic radiation we do every second.
That makes me wonder. Have there ever been any study of the genetic implications of being in space? Has an astronaut ever had one kid, gone into space for a while, then come back and had another kid? Would the second kid be genetically/noticeably different from his older sibling to an extreme degree? Would the astronaut’s genetic legacy be forever marred by larger-than-usual genetic mutation?
Since NASA likes to study every possible aspect of space travel, it seems like it’s something they’d have looked into, but I can’t turn up any kind of study or report.
I’d be willing to kick in five bucks to fund a test study. Anybody got any rocket fuel?
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### Author:  [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)
#### Post date: [August 28, 2009, 3:10am UTC](https://boards.straightdope.com/t/austronaut-genetics/507993/2 "2009-08-28T03:10:15Z")
> [@wierdaaron](#):
>
> Unless I am wrong, the major (if not only) thing that causes our DNA to change over time is cosmic and solar radiation. Cosmic rays assault and change our DNA slightly every moment, which is why 2 people can never produce the same offspring on two separate occasions (this can be evidenced by my aunt and her 13 kids). fuel?
This is not why siblings are different. A sperm carries 1/2 of the father’s DNA; no two sperm from that father carry the same half. Likewise for the mother: each egg carries half of her DNA, but no two eggs carry the same half. This is why no two siblings conceived of different sperm/eggs carry identical DNA.
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### Author:  [@jackdavinci](https://boards.straightdope.com/u/jackdavinci)
#### Post date: [August 28, 2009, 3:13am UTC](https://boards.straightdope.com/t/austronaut-genetics/507993/3 "2009-08-28T03:13:40Z")
Not sure if these kind of studies have been done, but I doubt that they would be more useful than earth bound studies of all radiation effects.
> [@wierdaaron](#):
>
> which is why 2 people can never produce the same offspring on two separate occasions (this can be evidenced by my aunt and her 13 kids).
That people never produce the same offspring has nothing to do with mutation. During fertilization, each of the parents sex cells only has 50% of the parent’s genetic information. These sex cells are created by meiosis, a process by which normal cells randomly get rid of half of each chromosome. Some variation is achieved by chromosomal crossover - parts of each chromosomal pair will switch places with their corresponding spot on the other pair.
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### Author:  [@wierdaaron](https://boards.straightdope.com/u/wierdaaron)
#### Post date: [August 28, 2009, 3:30am UTC](https://boards.straightdope.com/t/austronaut-genetics/507993/4 "2009-08-28T03:30:51Z")
I needed _some_ excuse to mention that I have an aunt with 13 kids.
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### Author:  [@Noel\_Prosequi](https://boards.straightdope.com/u/Noel_Prosequi)
#### Post date: [August 28, 2009, 3:45am UTC](https://boards.straightdope.com/t/austronaut-genetics/507993/5 "2009-08-28T03:45:14Z")
Fundamental problem here is that DNA mutation is not the reason siblings are not identical.
Grossly simplified explanation follows.
We each have 23 pairs of chromosomes in each cell, subject to some important exceptions. Chromosomes are essentially very long DNA molecules. The chromosome pairs can be reliably differentiated from other pairs, and are numbered 1-22 and XY. It is possible to locate sites on chromosomes where a given section of DNA codes for a protein. That site is a gene. It will appear at the same place on both versions of the chromosome in all people. Because the chromosomes come in pairs, there will be two versions of the gene in each person. One version will have come from Mum and one from Dad. The two versions may well, of course, be coincidentally the same (in which case the owner of the genes is “homozygous” for that particular gene).
Now we come to one of the “important exceptions”. When a sperm cell (or for that matter, an ovum) is created it only has 23 individual chromosomes, not 23 pairs. If this were not the case, chromosome numbers would double in each generation, rapidly resulting in an unfeasibly large number of them in each cell.
The important issue is how these individual chromosomes in sperm cells are created. A process called recombination occurs whenever a sperm cell is created, whereby information that had been on both components of a pair of chromosomes is shuffled around. Some information might come from the “first” of a pair of chromosomes, some from the “second” - it’s all fairly random. The amount of information in a sperm cell is half that of the information in a regular cell, but how that halving is achieved is essentially random.
The result is a sperm cell that is essentially unique, because of the large number of possible ways of combining all the various paired pieces of information in a person’s genome. The process is called [meiosis](http://en.wikipedia.org/wiki/Meiosis).
You can see this in a small way when you recognise that some sperm are X and some are Y, otherwise all children would be the same sex (ova are all X, because all women are XX)
Thus, all the sperm cells in the body of Dad are related (because there is only a finite pool of information from which they can have come) but are nevertheless each unique because of the recombination process that is part of meiosis. This is because of the huge number of different ways the process of “this gene from locus so-and-so on chromosome pair 21 and that gene from locus so-and-so on chromosome pair 16” can occur. The same is true for the ova in the body of Mum.
And that is why brothers are all different, as are sisters. Dad’s body mixes and matches the DNA from _his_ parents as does Mum’s in such a way that means that Mum and Dad’s children will be related, but unique.
If it were not for recombination, all siblings would be mostly identical.
If the cause of differences between siblings was DNA mutation occurring between each birth, then the genome would be so unstable as to be unworkable.
DNA is robustly resistant to change. Its almost magical processes of self-replication have error checking mechanisms. Mutations that do occur in the genome are (relatively) rare. Those mutations which translate to viably coding for proteins are rarer still. Those mutations which code for proteins that are compatible with life in a viable offspring still rarer. Evolution requires a balance to be struck between the generation of a reliable, stable genome (so that we have something stable to pass on to the next generation) and having some modest capacity for change (so there is sufficient variation in the species’ gene pool to allow for selection to take place).
So…looking at an astronaut’s offspring for genetic change in the way you suggest is not likely to be productive, because all offspring are genetically unique for reasons that have nothing to do with mutation. Of course, a mutation may occur as a result of space flight, but it has to have affected a sufficient number of sperm (there are 10s or 100s of millions in an ejaculation) to result in noticeable change which is capable of being distinguished from non-space related mutagens (astronauts, and the rest of us, are exposed to mutagens on earth all the time).
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### Author:  [@flodnak](https://boards.straightdope.com/u/flodnak)
#### Post date: [August 28, 2009, 6:42am UTC](https://boards.straightdope.com/t/austronaut-genetics/507993/6 "2009-08-28T06:42:51Z")
Elena Andrianovna is the daughter of [Valentina Tereshkova,](http://en.wikipedia.org/wiki/Valentina_Tereshkova) the first woman in space, and her first husband Andrian Nikolayev, also a cosmonaut. She is as far as I know the only person whose parents had both travelled in space before her birth. At the time, some people, particularly conservative elements in the Soviet air force who didn’t like the idea that a woman had flown in the first place, speculated that Tereshkova’s eggs were irreperably damaged by her space flight, but little Elena was born healthy and normal and is now a 45-year-old doctor of medicine.
It’s possible that Tereshkova and Nikolayev experienced at least some pressure to marry and have a baby together, as they were the only two unmarried cosmonauts. In any event, they had no more children and eventually divorced.
(Personal note: I’ve met Tereshkova! 😃 She’s, um, shorter than I expected.)
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### Author:  [@dtilque](https://boards.straightdope.com/u/dtilque)
#### Post date: [August 28, 2009, 7:15am UTC](https://boards.straightdope.com/t/austronaut-genetics/507993/7 "2009-08-28T07:15:47Z")
> [@wierdaaron](#):
>
> Unless I am wrong, the major (if not only) thing that causes our DNA to change over time is cosmic and solar radiation.
You are wrong. There are a number of chemicals, called [mutagens](http://en.wikipedia.org/wiki/Mutagens), that cause DNA to change. Most of these are also carcinogens, since cancer is often caused by mutations.
> [@](#):
>
> Here on earth, we’re protected from most of the cosmic radiation out there by our magnificent magnetic field. The skuttlebut is, though, that when you leave earth you’re no longer subject to that aura of protection. I’ve heard that an astronaut on a space walk (like, say, repairing Hubble) receives something like 1,000 times the cosmic radiation we do every second.
It’s not just the magnetic field, but also the atmosphere that protects us. Short wavelength e-m radiation (xrays, UV, gamma rays) are mutagenic, but are largely blocked by the atmosphere.
The magnetic field blocks most charged particle radiation, although some of that still gets through. The basic rule is that the higher you go, the more radiation you get.
Astronauts do get lots more radiation exposure while in orbit, even though their orbits are still within the magnetic field. But especially when they go through the [South Atlantic Anomaly](http://en.wikipedia.org/wiki/South_Atlantic_Anomaly), which is an area where the magnetic field is exceptionally close to the Earth. The Hubble Telescope is significantly further out than the shuttle normally goes, so there will be even more exposure on those missions. BTW, even airline crews get more exposure from frequent flights through the stratosphere.
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### Author:  [@Smeghead](https://boards.straightdope.com/u/Smeghead)
#### Post date: [August 28, 2009, 3:30pm UTC](https://boards.straightdope.com/t/austronaut-genetics/507993/8 "2009-08-28T15:30:36Z")
1 - many of your premises are faulty, as has been explained
2 - astronauts don’t spend all that long in space
3 - it’s quite simple to replicate that level of radiation exposure here on earth
4 - I would be surprised if earthly studies haven’t been done to show that that level of radiation for that duration is safe for astronauts
5 - what kind of change would you expect to see in their kids?
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### Author:  [@Smeghead](https://boards.straightdope.com/u/Smeghead)
#### Post date: [August 28, 2009, 3:59pm UTC](https://boards.straightdope.com/t/austronaut-genetics/507993/9 "2009-08-28T15:59:18Z")
Forgot to include,
6 - The number of astronauts is so small a sample that we would likely be unable to draw any significant conclusions about what is essentially a random process by studying them.
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### Author:  [@Mangetout](https://boards.straightdope.com/u/Mangetout)
#### Post date: [August 28, 2009, 7:17pm UTC](https://boards.straightdope.com/t/austronaut-genetics/507993/10 "2009-08-28T19:17:15Z")
Austronaut = Antipodean spacefarer?
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### Author:  [@Elendil\_s\_Heir](https://boards.straightdope.com/u/Elendil_s_Heir)
#### Post date: [August 28, 2009, 7:25pm UTC](https://boards.straightdope.com/t/austronaut-genetics/507993/11 "2009-08-28T19:25:29Z")
Could be. Or… Ahnuld was an austronaut in _Total Recall_, wasn’t he? He went to Mars, after all.
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### Author:  [@Der\_Trihs](https://boards.straightdope.com/u/Der_Trihs)
#### Post date: [August 28, 2009, 7:35pm UTC](https://boards.straightdope.com/t/austronaut-genetics/507993/12 "2009-08-28T19:35:11Z")
> [@dtilque](#):
>
> You are wrong. There are a number of chemicals, called [mutagens](http://en.wikipedia.org/wiki/Mutagens), that cause DNA to change.
I’ll also add retroviruses, which even carry chunks of DNA between species.
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### Author:  [@Mangetout](https://boards.straightdope.com/u/Mangetout)
#### Post date: [August 28, 2009, 7:47pm UTC](https://boards.straightdope.com/t/austronaut-genetics/507993/13 "2009-08-28T19:47:11Z")
> [@Elendil\_s\_Heir](#):
>
> Could be. Or… Ahnuld was an austronaut in _Total Recall_, wasn’t he? He went to Mars, after all.
Or did he…?
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### Author:  [@Elendil\_s\_Heir](https://boards.straightdope.com/u/Elendil_s_Heir)
#### Post date: [August 28, 2009, 10:21pm UTC](https://boards.straightdope.com/t/austronaut-genetics/507993/14 "2009-08-28T22:21:04Z")
> [@Mangetout](#):
>
> Or did he…?
:: dramatic chord of music ::
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### Author:  [@Lucas\_Jackson](https://boards.straightdope.com/u/Lucas_Jackson)
#### Post date: [March 15, 2018, 4:11am UTC](https://boards.straightdope.com/t/austronaut-genetics/507993/15 "2018-03-15T04:11:18Z")
> [@wierdaaron](#):
>
> Unless I am wrong, the major (if not only) thing that causes our DNA to change over time is cosmic and solar radiation. Cosmic rays assault and change our DNA slightly every moment, which is why 2 people can never produce the same offspring on two separate occasions (this can be evidenced by my aunt and her 13 kids).
>
> Here on earth, we’re protected from most of the cosmic radiation out there by our magnificent magnetic field. The skuttlebut is, though, that when you leave earth you’re no longer subject to that aura of protection. I’ve heard that an astronaut on a space walk (like, say, repairing Hubble) receives something like 1,000 times the cosmic radiation we do every second.
>
> That makes me wonder. Have there ever been any study of the genetic implications of being in space? Has an astronaut ever had one kid, gone into space for a while, then come back and had another kid? Would the second kid be genetically/noticeably different from his older sibling to an extreme degree? Would the astronaut’s genetic legacy be forever marred by larger-than-usual genetic mutation?
>
> Since NASA likes to study every possible aspect of space travel, it seems like it’s something they’d have looked into, but I can’t turn up any kind of study or report.
>
> I’d be willing to kick in five bucks to fund a test study. Anybody got any rocket fuel?
Here you go: [https://www.newsmax.com/newsfront/scott-kelly-nasa-space-station-dna/2018/03/14/id/848738/](https://www.newsmax.com/newsfront/scott-kelly-nasa-space-station-dna/2018/03/14/id/848738/)
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### Author:  [@Little\_Nemo](https://boards.straightdope.com/u/Little_Nemo)
#### Post date: [March 15, 2018, 4:58am UTC](https://boards.straightdope.com/t/austronaut-genetics/507993/16 "2018-03-15T04:58:22Z")
I know it’s an old thread but I want to point out this is a fairly common practice. Not for astronauts but for plants. You expose plants to radioactive material in order to increase the rate of mutations. Some plants may die, some might remain unchanged, and a lot will have useless mutations. But if you’re lucky, some will have a commercially useful change.
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### Author:  [@Chronos](https://boards.straightdope.com/u/Chronos)
#### Post date: [March 15, 2018, 11:24am UTC](https://boards.straightdope.com/t/austronaut-genetics/507993/17 "2018-03-15T11:24:11Z")
Note also that any mutations will only be passed down if the mutation occurs in one of the cells in your gonads, which are a fairly small target compared to the body as a whole. You’re much more likely to get some cancer or another, since you can get cancer in almost any part of your body.
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### Author:  [@jasg](https://boards.straightdope.com/u/jasg)
#### Post date: [March 15, 2018, 3:26pm UTC](https://boards.straightdope.com/t/austronaut-genetics/507993/18 "2018-03-15T15:26:22Z")
Have we learned nothing from all those pulp SciFi mags and B-movies?
Clearly, Scott Kelly has been infected by an alien life form - any day now his skin will turn green and his eyes start to bug out 😃
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### Author:  [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)
#### Post date: [March 15, 2018, 3:49pm UTC](https://boards.straightdope.com/t/austronaut-genetics/507993/19 "2018-03-15T15:49:50Z")
The article is about _gene expression_–the activity of the genes, not the genes themselves changing. If seven percent of his genes had mutated, he would be incredibly dead. (Gene expressions change according to the environment all the time, such as eating sugar causing the body to produce more insulin and fear causing it to produce more adrenaline.)
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### Author:  [@Irishman](https://boards.straightdope.com/u/Irishman)
#### Post date: [March 15, 2018, 4:51pm UTC](https://boards.straightdope.com/t/austronaut-genetics/507993/20 "2018-03-15T16:51:52Z")
> [@Noel\_Prosequi](#):
>
> Grossly simplified explanation follows.
I find it amusing that your grossly simplified explanation is longer than everyone else’s explanations combined.
> [@Lucas\_Jackson](#):
>
> Here you go: [https://www.newsmax.com/newsfront/scott-kelly-nasa-space-station-dna/2018/03/14/id/848738/](https://www.newsmax.com/newsfront/scott-kelly-nasa-space-station-dna/2018/03/14/id/848738/)
That article starts with a line that reads strangely: “Astronaut Scott Kelly’s DNA was altered during his year in space, and seven percent of his genetic code remains changed, according to research conducted by NASA.”
“remains changed”… Isn’t that an oxymoron? Someone flubbed that sentence.
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