Comment Nonfunctional only is usual (Score 1) 11
When you damage functional DNA, the most common result is death rather than spider powers or hulk.
I think of DNA as instructions on how to do things and if you change the instructions for most things, it just dies.
Heart, lung, intenstines, veins, pancrease, etc. all matter a lot. Not to mention forgetting how to make bones, muscles, tendons, etc.
Yes, there is a 1 in a 100 case where you get a slow, drawn out death. And a 1 in a 1,000 where the change is minor enough to simply weaken you. And of course a 1 in 10,000 chance of a merely cosmetic difference and a 1 in 100,000 chance of minor improvement.
But all the other times, what you get is death.
Evolution is a cruel mistress. She makes the honey badger look empathetic.