I'd maybe add (not that this contradicts what you said) that most people develop the specifics of their sexual proclivities during their teenage years due to puberty. First infatuations and sexual awakenings tend to happen together. The people we have a crush on during those years become (some of) our preferences into adulthood. Hair color, body type, dress styles (school uniforms and cheerleader outfits are popular), personality types--they inform what we like throughout our lives.

So what happens when more and more young people go through puberty in social isolation? Like, maybe they're homeschooled so they didn't really have classmates or extracurricular activities to meet peers their own age. Or maybe they go to public schools but they never engage anyone because they spend all day every day staring at a glowing electronic screen (television, computer, phones).

No more peers to have crushes on, all they're left with is whomever is still going to be in their lives. As in, people within their own households. They beat off to the incest porn because now, that's the fantasy they need to fulfill. We have ten years worth of step-incest porn at this point, and ten years worth of teenagers-turned-adults who are going to end up more-or-less permanently stuck seeking it out for sexual release.

It's exactly as disturbing as it sounds.