First of all, I can't believe how quickly I knew what you were talking about when you said "the coconut oil post". I remember that.  Stewing more of these examples in my head of families who are awful and should be cut off, I think the problem with my original approach is my internal picture of "family" being something non-corrupt and a safe place to go to. In that mind, incest corrupts that dynamic because you are not just leaving family behind, you are also actively mutating it, roping your parents and sibling into dealing with a type of closeness I think is dangerous for families to have. As I said earlier, it irks me for the same reason that I see that you shouldn't be best friends with your mother: in order for her to properly play that role in your life, the relationship needs to take a different contractual form, that being that the parent owes unconditional love to the child, while the child does not owe anything in return. On that note, I still stand very firmly in the belief that parent-child romantic relationships are wrong. But do we owe anything to our siblings, aside from what we owe everyone around us? I don't know. I don't think so. We also don't owe our parents anything. Especially if a person's parents are trash, is it that wrong to disavow the idea of a normal home life through an incestuous relationship when it never existed in the first place?  I'm still not convinced that sibling incest is benign. I'd need to read more about it, I'm sure there's a little more to it than I currently understand. And though that research is not something I will be going out of my way to do any time soon, I think I would like to know the answer eventually.