ScreamingNinja said:
If you can look at your younger sister like this, then you've got some wires crossed somewhere. There're so many other people out there in the world, why would you even do it?
Honestly, I don't think there's an excuse for it. Something's simply not right in your head if you do this. Same if you have sex with animals. You're missing some screws.
I'm glad you said it. This isn't a knee jerk reaction, either. Genetic diversity was always a good argument against it, but the fact is that it's still wrong. Emotional attachment based on what should normally be a platonic relationship is unhealthy, and will likely cause continuing emotional issues. Humans are biologically wired to subconsciously think of sex for the procreation, even if it doesn't necessarily lead to procreation. They are also biologically wired to protect genetic diversity. Therefore, if neither warning light is blinking, the wires are crossed, which means that other wires are probably crossed too.
Here's another way to look at it: Society deems it as bad, normally. It's not a societal lag like homosexuality, either; it's a severe social taboo. People normally feel remorse, not because something is necessarily bad, but because society deems it bad. If a person is not feeling remorse, they're sociopaths (sociopaths are not necessarily violent, they just don't feel remorse). If a person is feeling remorse, then that remorse is going to be causing them to function abnormally, and can leave lasting mental effects.
The two above together combine to make only a fraction of the argument against incest. This really isn't a "If it's not bothering me" type thing. Sure, I'm fine with live and let live on issues. If an incestuous relationship is occurring, it's not my job or place to deal with it. It may not be hurting me, it most certainly IS hurting someone, whether they realize it or not.
On a completely different note, the reason I quoted the above post is because he said that it's wrong. There's a lot of push nowadays to just turn your head and ignore everything so long as it isn't hurting anyone else. We need more people who are willing to just say "Yeah it's wrong." Is it hurting anyone? No. Is it still wrong? Yep.