Thinking about it, my personal moral code or kinks/squicks have never been (significantly) changed due to fandom. I've been very open in regards to sexual practices for as long as I can remember, so I never had many real squicks to begin with. Those I do have - scat, bestiality, non-con, mostly - have not changed.

I do draw lines between real life and fiction mostly when it comes to consent, not so much to practices. Fiction, in my opinion, is fiction for a reason - I fully support everyone's right to write (and read) what they want, even if it's something I personally find objectable. So as long as they warn properly, allowing someone who doesn't want to read something a way to avoid it, anything goes. Obviously that is not the case in real life (including photography or movies, i.e. things actually involving living beings). To stick with the example of incest, I don't mind it in fiction, but it's a more difficult issue in real life. I don't believe it's inherently bad if blood relatives are romantically involved/ sleep with each other (strange, yes, but whatever). However, there is such a huge problem with (full and informed) consent in real life incest, since family relationships (especially if they're cross-gen) have such inherent power dynamics, that I wouldn't approve of them under many circumstances.

Dub-con is similar, it can be hot in fiction, but is an absolute no-no in real life.

... I'm trying to formulate a good conclusion to my thoughts, but yeah, that's pretty much it. :)