I regularly get questions about how in the world LinkedIn knows who you might know… people that you are not connected to but show up in the People You May Know section. I wrote to a contact at LinkedIn who gave me permission to paraphrase his response… which is this (this response was to my question from someone who saw some surprising suggestions in the box):
If you never imported your mail account contacts then LinkedIn really has no way to get them.
If you import your contacts from any system then LinkedIn can make the logic connections between YOU and your imported contacts. Makes sense, doesn’t it?
The algorithm (logic) for the People You May Know section is proprietary – it’s their “secret sauce” (or what we in IT call “black box”), and is a constant work in progress.
There is an analytics person who scours LinkedIn data looking for correlations between connections to try to figure out why they connected.
Some of the logical, easy-to-figure-out connections would come from asking questions like:
Was the person you may know a common person they both knew at their most recent job? Someone at their first job? At college? Etc.
As you would expect, LinkedIn has revised this logic/algorithm over the years. Different factors would become the most important ones based on how the network changes and their understanding of it. Their goal is to deliver those “how did they know that” moments in a way that makes sense to you (not freaks you out).
Finally, my contact made it clear that the contacts that show up in that box are not coming from some access to any of your non-LinkedIn accounts without your approval.
Perhaps when it is most eerily correct, it’s more a function of them getting their algorithm correct I’m pretty confident that they are not hacking into my mail system, nor are they allowed access by my mail providers.