I think a more plausible explanation is location reporting from your phone or laptop.

Unfortunately, Facebook's official explanation of "People you may Know" is chalked up to "many other factors". So I don't blame you for speculating.

https://www.facebook.com/help/163810437015615

I wish they would update this page to be more transparent. If they are in fact using LinkedIn's network (I just saw your comment below about co-workers which are not in the same geographical location), I hope they let users know and make a feature to opt-out of mixing it with Facebook.

Facebook looks at your phone contacts, recent calls, and saves that info. It does the same for your colleagues.

Another possibility is that your co-workers are browsing your public profile details without adding you.

Really you're leaking identifiable data all over the place. There's no way to tell what Facebook picked up on.

There are other options, e.g. proximity. Or your colleagues have added your email or phone number to their contacts which messenger/facebook can access. It's a creepy feature but Linkedin selling their network graph is too far fetched in my opinion.

Or accessing Facebook from same IP address.

I thought about it. But it gets creepier. Former colleagues in different geographical locations who don't have my phone number/contact info but are only connected on linkedin appear in Facebook.

Does your company funnel every location through the same internet connection? And some people put their employer's name on Facebook. They could be determining from your colleagues in close proximity which company you work for and then connect you with any others they are aware of. Still creepy but perhaps not as scary.

Could it also be because they looked at your profile?

I have also noticed this recently.

I think, and hope, that this will cost LinkedIn dearly.

Also possible they are identifying folks you are interacting with via audio.

http://www.independent.co.uk/life-style/gadgets-and-tech/new...