i rarely think of genre when brainstorming and coming up with a story. even when i do, while i'm writing a story i may find i want to shift genres, tell the story in a different light.
I do sometimes think, okay, what kind of idea is it? Am I going to write it Science Fictiony, or is it going to be allowed to stray into the Fantasy realm? Because, for me, there is a distinction in how the story progresses. Fantasy stories are allowed to get all magical, whereas in SF I have to pretend to justify the science somehow, mostly. But it's more a frame for me to work inside than it is for the reader/publisher/whoever.
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And it's good to have an idea of genre so you can keep an eye on market trends. (I don't advocate writing to trends, but I believe it's helpful to be aware of them.) What's hot now probably won't be the Awesome New Thing in six months. Can let you know what kind of road you'll be traveling.
Hey to those of you who feel it's easy to figure out what genre a story is, I challenge you with this dilemma:
A memoir (all material factual) half of which details a near-out-of-body experience that reads exactly like a fantasy thriller. Now what genre is that?![]()