Ask LH: How Does Facebook Know Who My Old Friends Are?

Ask LH: How Does Facebook Know Who My Old Friends Are?

Is there a way to work out where Facebook gets its “suggested friends” lists from? I recently started getting some very specific suggestions which Facebook could only know if it had access to my SMS messages from some years ago. I have no common friends with them and these people are no longer part of my life for a reason. I’m worried that these people may be seeing me as a suggestion too which I absolutely don’t want.

There’s also a large number of work contacts and people I generally don’t want on my Facebook being suggested and I have no idea how Facebook knows these connections. Anything I can do? Thanks, Creeped Out

Dear CO,

Facebook doesn’t explain its algorithms to the public, which is one of the many reasons it has a shady reputation. While the company has made incremental improvements to privacy settings over the years, this does not extend to how general user information is gathered.

In other words, if you want to use Facebook, you just have to accept weird friend suggestions as part of the privacy-sapping package. (There are however, some ways to lessen their frequency, which we’ll get to in a moment.)

There are numerous ways Facebook could have connected you to these people without resorting to nefarious phone hacking. It’s more likely that you share an identical school or workplace in your profile, or have “friends of friends” in common. If you gave Facebook access to your phone’s address book, it could also be making matches from there.

Because Facebook can map personal connections with a lot of data, the suggestions can happen even if you can’t see an obvious link. Until Facebook is forced to become more transparent with its information gathering, we’ll probably never know.

If the friend suggestions are really bothering you, your best bet is to simply remove them — when you hover your cursor above a suggested friend’s name, a little cross will appear. Click on that to make them disappear. You could also try removing address book contacts you’ve accidentally uploaded to Facebook which should get ride of the friend suggestions too.

Unfortunately, the only way to prevent your own name from appearing as a suggestion is to make your profile completely private. Best of luck!


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  • If someone added your phone number to the contacts list in their smartphone, via sim card import or manually the Facebook messaging app will sync that info to the db they use to pool people you might know.

  • Not confirmed, but I think FB shows people as suggested friends if they ever search for you or one of the individuals in your friends list. This has happened to me and was confirmed that the individual did search my name on FB (the only link that FB would know about).

    • Wow… I remember this exact comment I made and this exact article from aaaaages ago… Good to see that LH somehow managed to invent a time machine that brings posts/replies forward in time…

  • Yeah, I was a bit baffled by a suggestion recently, of a woman I built a website for like 5 years ago and have not really had contact with since. I guess EMC2’s suggestion is the most reasonable explanation for it.

  • Just stop using FB, Zuck does not care about you and most definitely does not care about your privacy, security or wellbeing. FB is all about selling you to the highest bidder.

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