[RajT88]

They maintain a shadow social graph, where they suggest friends to you which are more than one hop away.

I've been seeing people suggested as friends who are my customers at work. My FB account is pseudonymous, and has nobody work-related as a friend.

So - a few possibilities:

1. Someone at work tried to look me up by my cell, and they were friends with this person. (less likely)

2. I had a Facebook tab open when I connected to the VPN, and then someone at work who was friends with that person got associated with my egress IP since they connected to same VPN endpoint (more likely)

I have tested the IP address theory. Profile 1 connects to your home wifi network. Profile 2 on different machine connects to your wifi network. You now get friend recommendations of Profile 1's friends on Profile 2.

Nothing would surprise me when it comes to how Facebook builds its shadow profiles / shadow graphs. I wouldn't be surprised if they bought from data brokers and had things like your SSN's and historical home addresses and everything.