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I don't think the relationship of your other sites is having any effect on your rankings but it maybe Google post Panda is showing syndicated versions of your content as the most relevant. Finance and Making money online are very competitive niches and scraping/syndication is rife. I recommend that you firstly make sure that when you publish your blog posts you are pinging pubsubhubbub to make sure Google knows you are the originating source. Two questions: Which landing pages and keywords have seen the biggest traffic change in the past 6-12 months? Have you checked your competitor and your own link profiles for any recent changes ?