I've got a question: how come everyone is so down with incest? Like not literally everyone, but you know, EVERYONE.
Is it reasonable to maybe assume that it's such a mainstream fantasy desire because IRL people tend to not only love partners that look similar to their family instinctivly, but also somehow because within a family is often where people find love and acceptance more easily and naturally so they are more likely to secretly want to take the relationship with a sibling further and become partners with them? (Especially if they find getting a gf/bf nearly impossible amoung non family population, yet know that their sibling will always love them?)
And if all of that is the case, is it possible that the popularity of this kink is for a lot of people, maybe more than is fully realized, more of a secret real life desire, epecially for those who want to fulfill it but don't have a sibling?