Str82u - 1:26 am on May 11, 2013 (gmt 0)
Is that a fact or are you just guessing?
We have been penalized or flagged for doing something wrong and other SEO experts can't figure it out.
Are all the sites on the same server and linked together and with the same whois information? Not saying you're actually doing anything wrong there but from the algorithmic standpoint, G might be penalizing the sites as a private link network.
More importantly is what @TOI asked, "How long have they been online?" and I also agree that given the situation, I'd have gone with subdomains just to be sure G knows it's all the same business and not a private backlink network.