1- This isn't aimed at you Trope, I'm just using your words to say a few things about it.
2- The "problem" with incest is that it is based of taboos that simply aren't as Universal as those that have them think them to be. What do I mean? I mean that there are many places around the world untouched by the extremes of Puritanism that plagues other places. Places, where people have learned that "Shit happens" and sometimes feelings get mixed up, or, they realize that there really isn't anything that bad and while there are better options, it isn't the end of the world.
3- Accepting the Human condition and that we all are fallible and sometimes feel and do things that we probably shouldn't (I'll get to the why) is a measure of maturity, not only personal, but also as a culture. When a culture is immersed in Puritanism, it basically aims to deny the Human part, attempting to instill an ideal based on a rather punishing version of what some type of Divinity would want. In this they commit a violence that should appall them, but somehow doesn't.
4- The why we do what we maybe shouldn't, also why we maybe shouldn't, it is part of the consequences, rather than the actions. I don't only mean the potential for dangerous pregnancies. I mean also the serious imbalances in some of those relationships. The serious potential for abuse and for behaviors with borderline abuse. Yes, some of those relationships are consensual, informed and innocuous (mostly). There's always the potential for serious problems with public recognition and acceptance that can cause tensions that can destroy even the stronger bonds.
5- The Taboo, being a double faced situation, that acts as a deterrent but also as an attraction, as the proverbial Forbidden Fruit, we become easy prey. If at some level we feel that it is something that we should steer away from, and we do, in other levels we have this lingering nagging that tells us, "What If". I am sure that the vast vast majority manages to keep it as a "Intrusive Thought" and never act on it, or even let's it go any further than that. That there's a minority that are unable to resist the temptation or are placed in situations where the resistance stops making sense, I, personally, can't truly condemn. Unless, it is an abuse based thing. That doesn't fit in this scenario.
So... Is there really a Need to specify relationships in these or that terms, to either look for the Taboo or escape it? I don't think there is. The "fake" drama of woulda/shoulda/coulda, of an indecision caused by a Taboo that could simply not even exist, all that is simply put, lazy writing. Oh, but I like the tensions caused by people trying to deal with the temptations of the Taboo... sure... but does it have to be ALWAYS the same?
To be clear, I like the extra zest of a Taboo story, but, seriously, I also like when it is simply accepted as natural and drama-free.
The fact that there's a rather strong armed player that wants to force us all into a Puritiranical view and has the power to enforce it is NOT ideal. Sometimes I feel like donning my best Conspiracy Theorist garb and posit that they really want to create even more attraction for the Taboo by making it even more Forbidden. I dunno...
Peace
