I'm skeptical
Me and my brother were sitting in the garden and he was talking about a very random type of part to do with his car that he needed. His Android phone was sat on the table. I asked him if he'd googled to try and find this part online and he said he hadn't yet, but he would look later. We had our lunch then he checked his phone and low and behold he magically had an advert for exactly what he was after. The odds of it being a coincidence were extremely high and neither of us could believe it. Maybe it was a huge coincidence maybe he had googled it and they somehow got a cookie with the info. Safe to say he no longer has the facebook app installed....