They definitely use your contact lists. I have done multiple experiments with this. I first noticed about a year ago, people popping on my FB's "People you may

They definitely use your contact lists. I have done multiple experiments with this. I first noticed about a year ago, people popping on my FB's "People you may know..." list, and sure enough, the _only_ way they could link them to me was through my iPhone contacts. People like a guy who once fixed my roof, whose number I still had from years ago. As the original commenter said, LinkedIn seems to be even worse with this, creating those spooky empty default accounts for your grandmother or your child's best friend's dad. I think there will be a backlash against all this - surely it is a case of diminishing returns for the social media corps, combined with an ever-growing sense of _unnecessary_ intrusion by their users?