Another niggle: No, there are two
separate things here. The presence of screw dislocations is what makes (one) crystallisation
possible at otherwise impossibly small supersaturations, whether it be of DNA or of ordinary salt. (There ain't such an animal as a "lateral dislocation", by the way.)
I was suggesting that the primeval (two) evolution
of the helical DNA molecule itself, about which we seem to know little, could be linked to the helical character of a screw dislocation. But this is just an idle thought, since I know nothing about the evolution of huge molecules like DNA. But it must be quite a difficult process. Or life would spontaneously have appeared on Earth much more quickly than it apparently did.