Facebook Figured Out My Family Secrets, And It Won't Tell Me How

Among the friends Facebook recommended to Kashmir Hill as people she might know was Rebecca Porter, to the best of her knowledge a total stranger. Because Hill was studying how the "black box" of Facebook recommendations worked, she contacted Porter to ask what the connection might be. To her surprise, Porter turned out to be her great aunt by marriage, unknown to her because her biological grandfather had abandoned her father, who was adopted and never learned his biological history until adulthood. The company declined to explain how it might have connected Hill with Porter, though it did say that more than 100 "signals" go into making such recommendations. Hill's only option, if she didn't like the suggestion, was to delete it. Hill is continuing to study how these suggestions work.

https://gizmodo.com/facebook-figured-out-my-family-secrets-and-it-wont-tel-1797696163