I have being conducting an experiment. On July 5, 1993 The New Yorker published a cartoon by Peter Steiner of two dogs, one at a computer keyboard, with the caption "On the Internet, nobody knows you're a dog".
Our German Shepherd, Scully, has Pinterest account. I seeded it with pins of dogs and Pinterest figured out pretty quickly she liked German Shepherds but then the suggestions started to focus on long haired shepherds, which she is. Was that an unconscious bias toward those dogs on my part when I pinned for her (what am I saying!?!) or did Pinterest figure out something from her profile picture?
She follows my wife whose pins are about style - fashions, hair styles, and so on.
I'm not sure if those two are both related to what happened but Pinterest suggestions started to include a lot of GS puppies which I did not pin just to see what happened next.
And what happened next was an email from Pinterest: "we thought you might like this" with a picture of a squirrel . Result!