Consider also homosexuality. When, as a lad, I first became aware that there was such a thing, I had a powerful emotional aversion to the idea. But when I thought about it, none of the reasons that seemed to offer themselves in support of the aversion added up. Over several years of reasoning with myself, I--as it were--talked some sense into me, and the aversion went away. Again, not an atypical case.Yes. The bulk of the negative reactions to consanguinamory are Discredited Arguments #1 and 3. Next, people try to justify imposing their personal dislike by citing #18. When that doesn't work, they try to use #19 or 20.
So: contrary to what Haidt et. al. seem to claim there is no hard-and-fast asymmetry between the moral and non-moral cases. Maybe people more often rationalize rather than reason with respect to morality, but at best it's a difference in degree, not in kind.
As for roasted-chicken f*cking and consensual adult incest, these are cases way out on one end of the spectrum, best-cases for his position, not typical cases. As for consensual adult incest--brother-sister incest, to use Haidt's example--many people are just grossed out by it. Their only "reason" is ick. Personally, I don't think it's morally wrong, so it doesn't surprise me that people try to rationalize in that case. It's exactly what you'd predict even if you reject Haidt's position. It's just an ick case, people try to support an unsupportable position. Hilarity ensues.
People are going to have the feelings they have, including negative feelings towards some sexuality. When they really think through it though, they realize that their initial reaction is not a good reason to criticize others or attempt to deny them their rights.