I answered this in another thread, so I’m just gonna copy and paste my answer here. Sorry if the context comes off slightly odd, like I said it was originally elsewhere:

I’ve thought about the topic and I think I can answer why there has been a rise in step-porn.

I think it’s pretty simple: people are more isolated, and people now socialize online.

We’re simply seeing less of each other than we ever have (especially during the pandemic, but this isn’t specific just to that timeline). Whereas we used to go out and socialize and develop crushes in the real world, for a lot of people, especially a lot of young men, these days the vast majority, if not all, of the non-online social interactions they’re having with the opposite sex are within their own homes. And while our brains may be adapting to this new internet landscape well enough, I think our bodies are still lagging behind. When you’re an 18 year with raging hormones, the sexual drive extends beyond the reasonable brain. And so it attaches to what your libido recognizes as the other sexually viable candidates regularly in your sphere of influence: the women inside your own home. And thus they develop crushes on their mothers, their siblings, their stepsiblings, and are turned on by pornography that lets them indulge in this taboo but still very real crush.

And to be clear, I am attempting to explain the phenomenon, I am not attempting to excuse or justify it. Incest is gross and faux/step-incest may be biologically better but is still pretty socially/culturally fucked.

I’m just glad I grew up in the 90s before our lives had moved so heavily online.