[sharkbot]

I would suggest a change to your first sentence: "some stressors methylate genes, and those same genes may be methylated in descendants."

It is not a "mutation", at least not in the sense of a stable and heritable gene change. DNA methylation can be reversed, hence it is considered an epigenetic change, rather than a genetic change. The controversy over epigenetics seems to be about how long an epigenetic change can remain in a series of offspring, and how much of an impact an epigenetic change can have on the genetic material, the only long-term mechanism of heredity that we know of.

Caveat: IANABiologist