My nephew, when he was 9, brought a couple of friends home after school. He phoned up my sister at work to ask for the computer password, because "they needed to look something up for school", and my sister obliged. Based on the search history they left behind, his school taught some very advanced sex-ed to 9-year-olds. There were a couple of fairly innocent search terms, like 'naked girls' and 'boobs', but also a couple of proper specialist ones, like 'big black dick in white pussy' and 'dick in asshole'. So obviously, at least one of the little shits had some experience with porn and knew how to look up the kind of stuff he liked.