Fully half of my published fiction is in genres I never expected to write in, right up until the moment I started the stories. The interesting part is that I had the initial inspiration for them after asking myself the same question.
What question? This one:
"If I were going to write X, what would it be like?"
The first time, X=a fantasy world. I asked it because I'd been to a worldbuilding panel at a science fiction/fantasy convention, even though I didn't think the topic applied to me. The result was my first novel, Through the Veil, and its two sequels. (Through the Veil is out now, The Veil Restored is about ready to go to my publisher, and I've broken ground, so to speak, on The Veil Travelers.)
The second time, X=a superhero story. I'd just read one by Bracken MacLeod, a good friend who's an amazing author. I realized I'd never thought of writing a superhero story, and the question popped into my mind as I was lying down to sleep.
A few minutes later, as I was drifting off, I had an image in my mind of a little boy with extraordinary powers but developmental delays that made him non-verbal. I grabbed my laptop and, within minutes, had the basic plot of "Dax and the Red Eyes" laid out. This story now appears in Caped: An Anthology of Superhero Tales.
As writers, it's good to challenge ourselves to write something different from our usual – a different genre, a different type of main character, etc. I know it's helped me grow and explore and create new things. I challenge you to ask yourself this question the next time you read or watch something good that's outside of what you typically write. You may be surprised by the answer.