It's not mind reading, I explained how it works. You are friends with your parents on Facebook. Your parents buy the pillow. The pillow seller tells facebook t

It's not mind reading, I explained how it works. You are friends with your parents on Facebook. Your parents buy the pillow. The pillow seller tells facebook that your parents bought the pillow. Now Facebook knows that somebody who is your friend recently bought the pillow. Facebook may decide to show you an ad for that pillow because somebody who is your friend recently bought the pillow. The result may look like "mind reading", but it's actually very simple in terms of actual prediction.