Genre is a sticky subject, and suffice it to say that the way we categorize fiction is somewhat arbitrary and somewhat inevitable. If you think about it though, fantasy is the root of all fiction. Long before people began to write books, they huddled around the light of fires, under starry skies, in deep forests, or in the shelter of caves to tell their stories, and the impulse of fiction was already there in the myths and legends that were born among them.
There is an element of fantasy in all fiction. Modern stories are born from that same original impulse, to weave tales, to entertain and educate, and to find meaning in the world, and in the often extraordinary experiences of our lives. The best of the Fantasy genre can be directly traced back to the mythic structures that started it all, stories woven from the threads of an ancient dream. But fantasy is a kind of meta-genre in which fiction lives, and breathes, and is created anew.