Thanks Sam, as a computer scientist I am always thinking about the INFO content of the situation. Your explanation tells me where methylation occurs, but there is zero info carried in this, beyond the DNA itself, which is conserved. What is interesting is that sometimes those GC pairs are methylated and other times they are not. And the *INFORMATION* seems to be propagated to the child cell during mitosis.

Let me make a guess. The cell machinery by default will add a mirror methyl when it finds one, but it will do nothing if it finds zero methyls on either side of the pairing. Is that the propagation mechanism?

thanks!!