It's the email addresses. When you friends share their email contact list with Facebook, Facebook the list to find connections between people and suggest friends you might know. It's VERY intrusive especially when you have 2 online identities, a profession one and a personal one and Facebook keeps trying to tie them together with complete disregard for your privacy.

===== HOW IT WORKS =====

If someone has a Facebook account and shares their gmail or yahoo contacts with Facebook. Facebook will crawl through the email contact info and see if any of its already registered Facebook members' emails match the contact list. It will then put those matches up on the "People you may know" sidebar and suggest that you friend them.

That's what happened to me. I had 2 identities, one for family and relatives and one for my personal life & friends (goofing around, joking with friends). Facebook revealed my other identity to all my family and relatives. Some of them added me to their friends list and asked about my other name. I worked so hard to keep them separate but made the mistake with the emails. As soon as I changed the email the suggested friends recommendations stopped.

That. Really. Pissed. Me. Off.

I will never forget that, nor will I ever forgive Facebook for it. It was creepy and disrespectful.