Someone recently asked me why it's important to read in the genre they write, i.e., if you write science fiction, should you read science fiction, if you are a memoirist, should you read other memoirs?
In response, I asked him if he had a day job.
I asked him what he did.
He was an engineer.
I then asked, "If you'd never opened a physics book, how would that affect your job?"
He replied, "Well, I'd loose a great deal of feel for what it is I do and why things work."
Reading in your genre is not setting yourself up as a plagiarist. It is not distracting you from your writing. It is your homework, your business. If you are writing Fantasy fiction, you need to read as much Fantasy as possible. That is your job. You need to understand the conceits and structure of your genre. You need to know what's already out there. You need a background sense of what you should be aiming for in your finished product. You need to understand how to incorporate theme and foreshadowing into your prose. You need to understand how to organically set up a fantastical world. You can't work in a field you know nothing about. Well, perhaps you can, but you will likely be inefficient and ineffective.
I've heard people give writers advice to avoid reading about a subject they are writing, or in a genre they are writing because it will 'unduly influence their writing, and that they need to remain original.' I can't disagree more with this statement. This is like telling a painter never to look at other paintings. Sounds ridiculous, doesn't it? Studying other painters is part of what makes someone a great painter.
It's okay to be influenced. All artists have influences who have inspired their work. This is not a bad thing. This is an imagination booster, not a route to being a copycat. This is true even for screenwriters.
Read in your genre.