Ranging back to before Sophocles - who put the Oedipus "legend" into dramatic/literary form - and even Genesis - where Lot's daughters "rape" him in the night - incest has both facinated/repulsed.

But, isn't that the case with ALL "fetish" driven fantasy porn. Some LOVE it, some HATE it, some love AND hate it at the same time [whole guilt thing there], while others couldn't give a shit.

On many sites from which I download my free porn, some of the most popular files by # of downloads are "advertised" as brother/sister [usually "Russian" for some reason].

It isn't new. I recall the "Taboo" series from the 80s which was the first popular release of such a film I have heard of - there must have been others.

Even in what are non-fetish series you can get some references although these are usually of "step" relatives. For example in "University Coeds" I recall that Briana Banks [under the pre-surgery "Mirage"] has a scene with her "step-brother", and in "Barely Legal" Anastasia Blue fucks her "step-dad". There are countless others.

In the days before porn was available in the home and "Penthouse Forum" dominated my jerk-off aids, there were frequent brother/sister related letters, whether to the Forum or the column by Xaviera Hollander.

Even in the HBO series "Rome" they paint the future Augustus with so overt an attraction to his sister Octavia that she fucks him to try to extract a secret about Julius Caesar. [BTW I find Kerry Condon adorable!]

It ain't new and it ain't going away.