I was simply pointing out that any sexual relationship can cause harm wasn't singling out Genetic mutations specifically.It's kinda far fetched to say that normal sexual relationships cause genetic mutations in the scale that inbreeding does, don't you think? Ofcouse there's always a small change for some serious disfiguration or disease for a baby of a normal couple, but the chances are much higher with inbreeding.
Education.Let's say incest is allowed. How would you monitor them? How would you ensure they use a rubber?
People know the risks involved they can take precautions to prevent such risks, Same as homosexuals do.