As an aside, as long as the show's going on, the fandom will continue with it, even after the fact. It takes very little to taint something, it may sound petty, but that's the way the world goes. Incest is forever though.
I'm against incest and inbreeding (in case you accuse me of generalizing blindly) full stop, you can't convince me otherwise, and there's a good reason why Incest isn't covered in the LGBT (hopefully, what good can come of incest?) People who draw incest art claim to not support it in real life, but the fiction card cannot cover the ugly truth behind it. How can you explain a brother having a sexual attraction to his sister, or vice versa? If people can go after pedophilia with the same mentality from years ago, the same can be said for incest, because incest can inspire damage.
Incest whether it's fictional or not promotes a dangerous implication. Inbreeding. Whether or not it's further down the line, inbreeding leads to mental disorders. Tell me one inbred child cur