Incest can produce a deformed baby. Therefore it is unethical. Also incest tends to contradict our natural feelings. Meaning we tend not to desire it. We have a built in mechanism to guide us against it. — hope

Any coupling between unrelated partners can produce a deformed baby. Does that make all sex unethical?

What evidence do you have that we have "natural feelings" against incest? What is this "built in mechanism" which helps us avoid it?

I'm not in favor of incest, and I don't know anyone who is in favor. However, it isn't clear to me what it is that keeps us from having sex with related partners. If you met a sibling you had never previous known or known about, what would prevent you from finding this unknown relative attractive?

Any coupling between unrelated partners can produce a deformed baby. Does that make all sex unethical?

What evidence do you have that we have "natural feelings" against incest? What is this "built in mechanism" which helps us avoid it? — Bitter Crank

Incest can produce genetic problems at a much greater level then normal sex.

What percentage of the population desires to sex their siblings? Not many.