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This question already has an answer here:

The setting:

In the future, Earth's population reaches over 70 billion individuals, all living under an authoritarian government. Culture, tech level and wealth are pretty monolithic and everywhere is basically the same.

The government, for unknown reasons, administers unknown chemicals into the water supply. Pollution is widespread. Most worrisome of all, however, radioactive contamination is commonplace.

These toxins have resulted in disturbing and sometimes bizarre changes in human bodies. For example, hair falling out, and changes in skin and eye color.

The questions:

  • Can any of these changes occurring in an individual create mutations in the DNA and be passed on to a person's offspring?

  • Are there mutations caused by exposure that may not be present in the individual but would later show up in children that person has?

  • Are these “temporary mutations” (changes in DNA methylation for instance) or permanent ones (changes to the underlying DNA)?

I am mostly looking for an explanation for permanent changes to genetics such that these mutations get passed down to future generations.

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marked as duplicate by Renan, Elmy, Mołot, L.Dutch Dec 28 '18 at 4:17

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

  • $\begingroup$ Mutations, by definition, happen in the offspring, not in the affected individual. As for the intensity of expression, they will manifest themselves as any other mutation, such as, blond hair, blue eyes, reduced skin pigmentation, lactose tolerance, etc. If a man with wite skin, yellow hair and blue eyes has children with a woman with normal dark skin, black hair and brown eyes, how do their children look like? If those children in turn have children with peple of one or the other kind, how will their children look like? $\endgroup$ – AlexP Dec 27 '18 at 22:02
  • $\begingroup$ I'm talking about a mutation caused by the environment, namely exposure to radiation. $\endgroup$ – Ravi Mattar Dec 27 '18 at 22:05
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    $\begingroup$ I understand that. A mutation happening in an already formed organism is called cancer; you are not asking about this. Mutations which change the form or functions of the organism happen in sex cells, and manifest themselves in the offspring of the affected organism. $\endgroup$ – AlexP Dec 27 '18 at 22:18
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    $\begingroup$ @Renan, I agree that technically this is a duplicate of that question, but that question was so badly asked (and closed as a result) that it's a tough nut to swallow to close this one in its favor. Yes, ideally that first one would be fixed such that it can be reopened, but I don't see that happening. I'm going to vote to keep this one open and hope the OP fixes it to keep it open (Ravi! Ask one specific question. SE is not a discussion forum.) $\endgroup$ – JBH Dec 27 '18 at 22:47
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    $\begingroup$ Okay, I edited it. It may not be good enough for the question to stay open. It's still fairly broad. Hopefully it will 1) stay open and 2) you feel my edit reflects your intention. If not, edit it further, or do a rollback to bring you to where it was before. $\endgroup$ – Cyn Dec 27 '18 at 23:03
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Yes, it can.

In a somewhat simplified version: Radiation damages the DNA (and some other components) of the cells it comes into contact with. This interferes with the cells ability to divide among others - a process that is crucial to an organisms viability - and causes the cells to degenerate. If the dose of radiation received is below a certain threshold, however, the cell may survive and, in consequence, replicate its (now faulty) genetic material. This usually manifests as some form of abnormal growth (= cancer) in the person immediately receiving the radiation. However, since your DNA (or more accurately, the DNA in your sperm/ova) is used as a blueprint for your offspring, this damage is very much heritable, assuming that your reproductive organs received a sufficient dose of radiation. As a result, the offspring is now likely to be born with (or develop) a variety of mutations.

Usually, over the course of several generations, the extent of the mutations is decreased, assuming that a steady influx of healthy DNA from non-affected individuals slowly "thins out" the share of damaged DNA in the population. This presumes the existence of non-affected individuals on the planet and an end of the contamination, of course. However, if pretty much everbody were to have some sort of DNA damage, the mutations would most likely vary somewhat with each generation, due to the fact, that the extent and type of mutations of each individual (and therefore their combination) is usually unique and subject to randomness. Or, simply put: you probably would not have an entire country/planet full of red eyed, bald people or something like that, but you could have an entire country/planet of people with a variety of genetic disorders and mutations, that persist (although in variations) over long periods of time.

Edit: Removed the example, wasn't really helpful.

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Mutations can be acquired or hereditary. Acquired mutations are changes to the cells during lifetime and do not get passed on to the offspring.

Hereditary mutations are present in the parents egg or sperm cells and end up in DNA of every cell in the child. The mutation may or may not be expressed in the organism, as the mutated allele (piece of DNA) could be dominant or recessive.

Very small percentage of random gene mutations caused by chemicals or radiation have some meaningful effect. It takes thousands of failures for one working edit in the gene. Imagine opening a text file containing instruction manual for washing machine, typing in some random characters here and there, and getting a murder mystery as a result. It would even be difficult enough to get manual for different washing machine.

Spreading chemicals to environment is not very likely to manifest as pink hair or superpowers in progeny. Disease, infertility and death are more probable outcome.

More precise method must be used to introduce specific physical traits to offspring, something like gene altering virus perhaps.

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