Porn

Cindy Gallop, on a Ted talk, says that because of parental/school/society reticence, most children now learn about how to engage in sexual practices from hard core porn sites.
She has learned this from personal experience, because as an older woman, she chooses lovers in their twenties.

Because, as she says, these sites are owned by, run by, controlled by men, girls can find themselves obliged to cooperate in ways that they might otherwise not choose.