I did. But I never fantasised about actual incest, and certainly not with my family members. But fantasy incest in porn? Defo works for me.
I think lots of people are very capable of finding stuff hot as a fantasy while having zero interest in the reality. In fact, that's part of the appeal. If I'm just watching hot people have sex, it just kinda makes me sad I'm not having sex with them. But if I'm watching a kinky scene or something that is taboo because of the relationship of the characters involved, then I can find it hot without being disappointed it isn't real.
(and while I think there's something to your theory, the popularity of stepmom porn suggests it's not that simple, as most people who watch that probably had a mom)
That was... something. And I'd bet that Dan is on lemmy.