[linopolus]

> people know how to distinguish reality from fantasy/entertainment

So you think 15-year-olds who never experienced sex know how to distinguish reality (sex with a real partner) from fantasy (porn). Where would they have the knowledge how real sex is from?

[MarkMc]

From talking to their friends, or older siblings, or parents about their experience. By watching non-pornographic films where sex scenes are more realistic. By reading online accounts from other teenagers or adults. By talking about it in sex ed class. By reading articles in the newspaper such as "What Teenagers Are learning from Online Porn".

Moreover, the 15-year-old doesn't need to know what real sex is like in order to suspect that porn is fantasy. "Snakes on a Plane" is not treated as a documentary by people who have never travelled on a plane.