The use of "rewrite" is a bit misleading- what's being altered in this mechanism is an epigenetic tag that sits "on top" of one of the standard DNA bases; that an individual's epigenetics are altered as they go through life is well known. But since the underlying cytosine is (as far as we know) irrevocably bound to this tag, it has to be replaced by a different (but identical) cytosine. Its more like going over your…
Actually, it's been a thing for a while that we know the brain has somatic mutations which cause the DNA to differ from cell to cell. While the epigenetic tags are also affected, it goes beyond attaching tags. The brain literally rewrites its own DNA. https://www.genomeweb.com/sequencing-technology/single-neuro...
Better link without paywall and with link to actual article