Not specifically, but a couple general thoughts on mutations:Essentially every single trait we have is a the cumulative result of a whole bunch of mutations, just some were more recently acquired than others. Mutations are usually the removal or change of a single nucleotide, or the moving of a particular sequence from one location to another. Most mutations fall into one or more of the following categoreis:* No outward sign (e.g. mutations to non-coding regions of DNA)* Pretty minor (e.g. might hyperactivate or suppress a particular gene slightly, or slightly deform some copies of a certain type of protein being made, or some cosmetic change like eye color)* Detrimental, similar to "pretty minor", but just happens to influence things in a way that is harmful to the body (e.g. cancer, sickle cell anemia, color blindness, hemophilia, etc.).My impression is that the kind of major, beneficial, obvious mutations you see in Gamma World are pretty unusual, even (or ESPECIALLY) with exposure to high radiation. Usually those kind of major changes to traits (e.g. acquiring wings or an armored shell) are extremely unlikely to acquire via one single mutation. Such single generation "macromutations" are extremely rare, and instead these big changes almost always arise over many generations through the accumulation of many many smaller, benign mutations. Spontaneously growing gills (especially later in life) through mutation seems about as unlikely as cutting and adding individual letters and words at random from a New York Times financial article and having the result look like a Cosmo fashion article.Also, in a previous post, you'd mentioned how mental mutations would be common compared with physical ones. I can't speak to how common mutations of brain-coding genes are compared with those of the rest of the body, but I'm guessing they're not much more or less common. Also, unfortunately IMHO, we don't have any empirical (i.e. predictable, reproducible) evidence at this time that psychic abilities work. So it would seem that any mutations along these lines are extremely rare if existent.But, having said that, I LIKE the idea of these weird macromutations just showing up spontaneously (also like the idea of psychic abilities). It's a neat idea, so if you want a somewhat hard sci-fi explanation, how would you do that?One idea I came up with for my own game is that the "mutations" were actually engineered on purpose by humans in the before-time. There are retroviruses that were used for medical or cosmetic body modification back in the day and would implant these genes into humans or other organisms in some cases. In fact "uplifting" animals to human intelligence through this method was an intriguing challenge certain geeks couldn't resist.Normally these retrovirus treatments were done under controlled conditions, and the gene would only be "turned on" for any individual later with a particular activation trigger. Even though many of these retroviruses escaped into the general population, they were dormant without the trigger. But at some point gene hackers, terrorists, or just random mutation, might have managed to turn on these dormant genes outside laboratory conditions, even in individuals who didn't know they had the genes.... of course if you are going for a less "hard" sci-fi (Gamma World 4th Edition specifically claimed to be science-fantasy) or have other clever ideas, then you can certainly ignore this.
I love the idea of viruses being the cause for the mutations. I'm taking that and twisting it bit, so it will fit with the back story, and even provide some story seeds.Thanks!
Maybe some type of genetic engineering by some higher force that only manifests when activated?