I feel I'm being penalized for this. I have multiple sites across three hosting accounts, many of them aimed at the same or similar niches. The main problem is, I've registered almost all of them at the same registrar with the same who is (because I didn't know any better at the time). I suspect Google is now looking at the whois/whois history to find out the owner of each site, and is throttling my best ones. Last month I saw a distinct drop across almost all of them, even ones I haven't done any link building for for a long time - except the ones that are registered differently. Without closing or selling any of them, what's the most effective way out of this?