Any friends of yours who have installed any FB application will have uploaded your contact details. All FB needs to do is merge all of those profiles of you fro

Any friends of yours who have installed any FB application will have uploaded your contact details. All FB needs to do is merge all of those profiles of you from each of your friends and they will have a pretty accurate informational profile. Since many people have also added a photo of you to their phone contact entry, FB gets that too. Any time you visit a website that uses an FB Plugin, for commenting or sharing, FB drop a ghost profile cookie against you. If at any point you somehow leak your email address or cell number on one of those sites, they can now tie that ghost profile to a real person, thanks to your friends using FB, even when you don't.