ambris asked: So I'm curious as to why incest porn is a squick to you. I'm certainly not challenging, as I understand everyone's got their own fetishes--just curious as to your take on it, and why is seems like such a bad thing. Furthermore, I seem to recall you mentions that Celestia/Luna is the one exception to said squick--why is that?

(EDIT: Formatting and grammar.)

My rules give some explanation. (Everyone reads my rules, right? XD Maybe I should link to them every time I mark “RULES VIOLATION” or “RULES WARNING”.)

Anyway, my first encounter with incest in furry (EDIT: consensual incest) (not exactly pornographic) was in “Better Days,” a webcomic by furry artist Jay Naylor. The chapter I linked is where it happens (or is heavily implied, anyway). That was probably my main turn-off to incest in pornography.

More generally, sexual reproduction between closely-related individuals is disadvantageous in natural selection, because it does not create as much genetic diversity. So there is a biological reason for avoiding incest, which could lead (justifiably, in my opinion) to the cultural avoidance of it.

However, I think incest has more to do with the relationship between the individuals. Adoptive siblings are not closely related biologically, but I would still consider sex between them incest. Family relationships (I think) are asexual (going back to the biological advantage), and since the relationship between adoptive children and other members of a family is about the same, I would still consider it incest (and thus wrong to some degree).

Now the Celestia-Luna exception. You might be referring to this post, in which I mention the exception; I also mention it in my rules. In the rules, I point to a clopfic, “Tipsy” by Anonymous Pegasus on FIMFiction, whose handling of the incest desensitizes it a bit to the cultural taboo.

More generally, I make the exception because, frankly, Celestia and Luna have a pretty flimsy claim for being “sisters.” All we have for that is the first episode, but there’s no history of their birth, their parents, or their childhood. (I doubt that they’re even sisters in the traditional biological sense.) Like I said, I think incest is about the relationship, so the fact that there isn’t much of this relationship between Celestia and Luna makes it seem less like incest than if the “sister” claim is taken on its face.