@Swarty @peterdrake We don't know exactly yet. However methylated genes cannot be transcripted and - at least temporarily, disregarding the space they fill and the collision likelihoods caused by brownian movement - are therefore junk.

@Swarty @peterdrake There are also a lot of base pairs outside specific start and end sequences of genes that are never transcribed (introns). Those often consist of devolved ancient genes and viruses and may never function as genes but at least take up space and, because of their irrelevance, e.g. can absorb damaging radiation in favor of more important sequences.