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kjaxz8 t1_j09cjn7 wrote

Yes and no. For the most part, the answer is no. If you get cancer (due to mutated cells) caused by smoking this does not pass to you kids. The cells in your body are somatic cells and the mutations in the DNA of those cells does not get passed on. Your germline cells (sperm and eggs) are different. Potentially though those cells could acquire mutations which would be “pass on” but those cells are generally more protected.

Then there’s also the matter of epigenetics and imprinting. But that’s a long rabbit hole to go down. So the simple answer is no but the more complicated answer is kind of yes.

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Snapple207 t1_j0aczya wrote

While we're on the topic of sperm, doesn't the fact they're dying and being replaced frequently help prevent that as well? Unless the germ cells mutate, wouldn't sperm develop mutations individually?

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dkysh t1_j0aragh wrote

The sperm cells themselves are very short-lived. However, they do originate from spermatogonial stem cells that keep on replicating theough all your life.

In a cartoon, these stem cells divide into two cells. One of these daughter cells (cell A) keeps being a stem cell and the other not (cell B), begining a chain of divisions into further daughter cells that end up being a bunch of sperm.

New mutations appearing on cell B will only be found in one "round" of sperm. Mutations appearing in cell A are there to stay in all future rounds.

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kjaxz8 t1_j0b7yb1 wrote

Not really.

The frequent replacement of sperms cells is “helpful” in a sense to reduce the incidence of chromosome abnormalities like Down syndrome. For women, since they are born with all the eggs in their body, those eggs age with them and with that age it is thought that the chromosomes get kind of “sticky” and can have trouble dividing easily. This is why Down syndrome can be seen more frequently with older moms.

The same is not true to sperm. However, there are risks associated with advanced paternal age and those risks are associate with mutations. For example order dads have a high chance of having a kid with achondroplasia. This is thought to be related to the fact that the sperm of an older man has undergone more cell division leading to more chance of these small mutations.

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RedditScoutBoy OP t1_j0ap85k wrote

Thanks for explanation. It's good you brought in the discutions epigenetics. I read about the Hongerwinter where kids were born for many generations with health problems. Did this happen because of the bad nutrition and harsh condition the mothers lived in that period, so while the children were in womb some genes turned on or off to accommodate that? And are the "mutations" acquired through epigenetics imprinted forever in the genome or will they revert back once the external factor that caused that is removed?

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SaneButSociopathic t1_j0avpbn wrote

Like the parent comment said, it's a rabbit hole...

Some genes only remain epigenetically modfied untill the next cell division, others take multiple rounds, and still others can remain for 1-3 generations based on whether it was the father or the mother that carried the epigenetic modifications.

Simple example would be the Barr-body in women: most of the genes on one of the X-chromosomes in women get turned off shortly after germination - to keep the gene products balanced. But these modifications get reverted before one of the X-chromosomes can end up in an egg.

There is a lot about epigenetics we don't really understand but it seems extremely complex and setting up conclusive experiments is extremely difficult.

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shadowyams t1_j0becmq wrote

> I read about the Hongerwinter where kids were born for many generations with health problems.

This is a common misconception. The Dutch famine cohort consists of individuals born during or shortly after the famine (i.e., prenatal exposure to famine). People have shown that these individuals have elevated risk for several metabolic, cardiovascular, and psychiatric disorders (recent review), as well as persistent changes in DNA methylation.

Whether these epigenetic changes can be inherited is rather controversial. There's been some followup (search "transgenerational") in the Dutch cohort indicating some transgenerational effects. However, the effects aren't super strong, and, as far as I can tell, nobody's done the molecular biology to show that these effects are due to genuine epigenetic inheritance, or something more banal like parental or environmental effects.

> [A]re the "mutations" acquired through epigenetics imprinted forever in the genome ... ?

This would violate a lot of what we know of meiosis. Briefly, there's a lot of evidence indicating that chromatin state is wiped and effectively reset during meiosis through to embryogenesis.

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