Children learn about the mechanics of sex—or rather, that mechanics is the whole of sex—by watching women who may have been blood-tested and “verified” professionals, or who may have been so impoverished and desperate that they would have done literally anything for cash or drugs. Everyone is welcomed into this vast emporium of sex, and although the party line is that consumers bring their own desires to it and simply find the porn that suits them, the influence runs in the other direction.“If you’re with somebody for the first time,” a sex researcher at Indiana University helpfully tells her students, “don’t choke them, don’t ejaculate on their face, don’t try to have anal sex with them. These are all things that are just unlikely to go over well.”

Natasha Singh: Talk to your kids about porn

Certainly we can reserve judgment about private sexual behavior, but we can’t pretend that the things people expect to do in bed, or expect partners to do in bed, have not been hugely—almost entirely, by this point—influenced by online porn. No wonder so much sex between young people takes place behind a thick velvet curtain of alcohol—who wouldn’t want to be under anesthesia for some of these exercises? Culture is progressive and cumulative, and so is porn, restlessly seeking and crossing the next boundary, and thereby making whatever came before it seem tame and ordinary.

The problem is that there are some very old human impulses that must now contend with porn. One of them is the tendency of deeply troubled teenage girls to act out sexually as a kind of distress signal, an attempt to get the attention of adults who may not be getting the message that they’re in a crisis. Working this out within the closed world of a high school was painful, and almost always contributed to suffering, but it was something that could be transcended—eventually everyone moves on and the past settles into place.

But working out these impulses within the pitiless economy of the vast, global pornography industry is an entirely different proposition. Whenever a third party stands to profit from the sexual choices of a woman, a door is opened into another world, far beyond the high school, the disappointed parents, the town where she lives. It’s natural that this would become the venue for these troubled girls; porn is the main determinant of high-school kids’ sexual imaginings. Girls who feel uncomfortable or shamed about their body are deeply drawn to it. “I liked the attention I got,” Caitlin says of her first foray into selling pictures online; she liked “being called beautiful. I enjoyed it because it made me feel good about myself.”

The idea, vigorously maintained by a certain kind of young porn star and by her feminist defenders, is that it is entirely possible to be an adult performer yet in private life be someone who is perhaps modest, perhaps—as Caitlin describes herself—an “old-fashioned romantic.” It’s hard to imagine that it’s possible. I suppose the model for this might be marriage, in which a woman might be extremely modest and careful in her public dealings, but in bed with her husband is a fully sexual being, her desires as carnal and adventurous as anyone else’s. But it seems to me that a troubled teenager, desperate to be called beautiful, will have her sense of self deeply affected by work in that industry, which will quickly seek to put her in ever more extreme forms of on-camera behavior.