They say "you are what you eat", and I'm willing to say that "you write what you read".
I've noticed that my writing style changes according to what I'm reading, and I think it's something that happens to most writers. It's a subconscious shift, but it can definitely affect the way you write.
For example, when I was writing In the Days, I was reading the latest installment of Glen Cook's Garrett P.I. series, Wicked Bronze Ambition. The book is very film noir in style, but there is a lot of sarcasm and humor in it.
Well, reading back over some of the chapters of In the Days, I can see a lot of attempts to mirror the same dry humor that Mr. Cook uses in his writing.
However, when I read over my latest work--The Last Bucelarii: Blade of the Destroyer--I find that the tone has changed drastically. The book is filled with description and tension, and it's a much more somber story. There's almost no dry humor, even at parts of the story where a few jokes or quips would work. Why is that, I wonder?
Oh yes, it's because I'm reading both The Riyria Revelations and Words of Radiance--the latest offering in the Stormlight Archive series by Brandon Sanderson. Both of these books tend to be fairly solemn, with a writing style that is much more…serious, I guess. There is humor, but only in the dialogue. The rest of the book is solid description and narrative.
I'm willing to bet that all of the other writers out there have been influenced in their writing style by a book or books that they have read. I know that Scott Lynch's Gentlemen Bastards series definitely changed the way I view characters and their actions, and took me from the world of epic fantasy into the realm of dark fantasy in which my new character The Hunter lives.
What's the point of all of this verbal meandering? Simple:
"You write what you read, so read books that will sharpen your writing."
If you were to pick up books like Percy Jackson, Twilight, or Divergent I'm willing to bet your writing would soon begin to sound like the Young Adults novels you've been sucking down. If you read through 50 Shades of Grey, you'd soon be looking for ways to add sex scenes to your books. If you devoured the Night Angel series, you'd start to see assassins lurking behind every corner.
Not only will your stories change according to what you read, but your writing style will change as well. Those reading the Wheel of Time series will probably begin to write long, drawn-out descriptions and build elaborate worlds like Robert Jordan did. Anyone reading the short, sharp sentences used in Glen Cook's writing will definitely find their writing becoming snappy.
My advice for the day: read only GOOD books. Don't just pick up anything that you find. Don't read those unfinished manuscripts your friends are sending you. Find books written to professional standards with a writing style that you enjoy reading, and let them work through you to improve your writing style!