Sorry, but I MUST ask...
Question: OK, my favorite genres to write in are mostly fantasy and occasionally steam/dieselpunk, but what I really like to do in those genres (or any other, really) is to write storylines that are extremely... "unorthodox", I'll call it. I mostly write for fun, and because I don't think there is a publishing house in the world for my kind of writing (exaggeration, but you get the idea), I really would like to get published and my friends all want me to try it too. But a lot of my stories revolve around things that (I cannot stress this point enough) I DO NOT/HAVE NOT/WILL NEVER DO, but I just find myself fascinated by human taboos. I won't go through all of them here, but just ask you about one of the most prominent: Incest. Don't stop reading! I'm just really interested in the concept of true love found, but not looked for, between family. I mean, it is a fascinating thought isn't it, that you do not choose who you fall in love with? I write love stories, not erotica. The thing is every story of involving incest that I have ever read is either a tragedy, a work that condemns incest as automatically evil or sending some similar message, and it got really old really fast. There were even one or two where the couple in question could easily have made their relationship work and were sincerely in love, but chose to drop it for no other reason than people would not approve. BORING. I really want to try one with the couple finding a happy ending; after all, they did nothing wrong. They just happened to fall in love and they just happened to be related. Now, I repeat, I DON'T PLAY FOR THIS TEAM MYSELF, I JUST FIND IT INTERESTING SUBJECT MATTER. So, do you think this kind of story could be pulled off? If so, how? If not, why not? Do you know anything about genres like this that you think it would be good for me to know? I just need some professional help here. Thank you for any help.
I suspect there is at least a small market for everything the human mind can imagine. Sometimes what most of society finds unacceptable ends up being published in small underground publications. Fiction or nonfiction concerning drugs, alternative music, revolutionary politics, gender issues, art, horror, the occult, and all manner of sexual taboos
have at one time or other fallen into this category. Many of these, in later periods, came to be acceptable in fiction and most people now wonder what the fuss was all about. One person's depravity can be someone else's cutting edge. (With a few exceptions that probably belong permanently on the fringe.)
I'm not saying your idea is completely on the fringe. It always comes down to how you do it, the finished product.
Your question was whether you can pull off such a story successfully. No one can say it's impossible, but would be challenging to make it ring true for most readers. I'll just play devil's advocate here, so you can think about how you might address these issues...
Most female readers today would, I suspect, have a hard time imagining a scenario in which they would voluntarily have an incestuous relationship that would not feel at the very least creepy (to use a technical term). I'm not a psychologist or sociologist, but as far as I know, sibling incest is typically initiated by an older brother, and the imbalance in power is a key element that also makes it abusive.
I know that there were times in history when it was common practice for kings to marry their sisters. One explanation is that the Egyptian royal family raised boys and girls separately (because kids raised together have an instinct prohibiting sexual relations).
Another possibility is that the girls may have been pressured into it, as girls in polygamist cults are today. It's hard to imagine an empowered adult woman making that choice. Yet, if you want a happy ending, you can't have her forced into it.
Your challenge would be to create a scenario in which a) the sister is not forced or pressured into this relationship and b) the reader would not find it unbelievable that she would choose it. A female reader with no history of abuse and good self-esteem might find it hard to put herself into those shoes.
Now maybe you're writing a book primarily for male readers ... but then you still risk turning it into a "forbidden love," adult content storyline - a fantasy rather than something that rings true.
On the other hand, one can't deny that erotica sells. Look at Shades of Grey
Bottom line: you have to follow your muse, but to win over most readers, you have to find a way to make it seem plausible.