Does "it" refer to "the attachment"?

Context:

It was Razin, working with fellow biochemist Howard Cedar, who showed these attachments weren°Ot just brief, meaningless affairs. The methyl groups could become married permanently to the DNA, getting replicated right along with it through a hundred generations. As in any good marriage, moreover, the attachment of the methyl groups significantly altered the behavior of whichever gene they wed, inhibiting its transcription, much like a jealous spouse. It did so, Razin and Cedar showed, by tightening the thread of DNA as it wrapped around a molecular spool, called a histone, inside the nucleus. The tighter it is wrapped, the harder to produce proteins from the gene.

- Trait vs. Fate