I have an baseless theory that people that first has sexual experience when they were young or in strict households and had to sneak around and hide their relationships are more likely to want to chest because the "thrill" of hiding the relationship and tabbooness of it reminds them of their formative sexaul experiences.
Yeah that’s because many Gen-Zers and late millennials have grown up in blended families. I bet many of them have fantasized about bangin an older step sister or step mom and even stepdads fantasize about banging an adult step daughter. Then they look up that kind of porn on the web. The algorithms will push that genre up in the rankings and then producer will follow the trend to appear at the top of those rankings.