Assuming your content is unique and original, it is critical to take steps to protect and retain for your site the content authority that is rightfully yours. Unless there is a ranking issue, every page should be the content authority for any significant chunk of text from that content. This means that if your pages are not #1 for the snippets from the page, either the site is being penalized, or another site has the content authority for your text.
Loss of content authority will appear as a suppression of ranks for specific terms associated with the page/s involved. With a large site, page to page redundancy can destroy the content authority of the homepage. Some very simple oversights can usher in big headaches - like the null set redundancy.
With multi-site implementations it's important to keep the content authority local, or else your sites are competing against each other in a harmful way. The same danger results from uncontrolled affiliates who copy content from the site. If you rely on affiliates, you need a very strict policy restricting activity that endangers your content authority.
Branding All Content
One way to retain the content authority even when your content is stolen, is to embed your brand within the text of the content. This way, the branding elements have to be changed to use your content on another site effectively. If your site is high ranking site, be advised that your content will very likely get stolen (count on it), but branding offers a measure of protection that we strongly recommend.