Paedophilia, incest and such like is wrong, end of story. It just is. Like murder, you don't need to be told it's wrong to work out that it is.
I'm not sure the genetic argument is scientific when it's a one-off either. Women that delay having children until they are older increase their risk of having a genetic deformity. But it is the woman's choice.
There should be no choice for the other things mentioned above.
