Publishing houses are by nature conservative. They're businesses, which means they need to make money to stay in existence. Which in turn means they have to guess which books (of the hundreds of thousands written every year) are likely to sell—and they have to be right a good proportion of the time.
Now, one of the Horrible Truths about publishing is that no one in a publishing house actually reads the books they publish, except the editors who acquire them. Everything else—ad budgets, cover and book design, decisions regarding print runs, etc.—is based on what an editor can tell the other departments about the book. This means that responsibility for whether a book is successful or not will ultimately land at the editor's feet—because he or she chose it.
By and large, any editor would sell his or her soul to acquire a truly wonderful book. However, editors also work for the publishing company—the latter being by definition a soulless entity whose only concern is the bottom line. That being so, any editor is constantly walking the narrow line between wanting to acquire a marvelous, unique book—and the nagging, ever-present question: Can we sell this?
This is a lot of pressure for the poor editor. On the one hand, they really, really want fresh, new, exciting, wonderful books. On the other hand, if the books they choose don't sell well, they'll get fired. The fresher, newer, and more exciting a manuscript is, the longer the odds against its success. Why is this?
Well, if I may lapse into analogy for a moment, consider restaurants. Lutece vs. McDonald's, to be specific. Lutece is a four-star, world-renowned restaurant, whose menu is the absolute definition of "gourmet." People eat there and swoon. McDonald's…well, the food is tasty, cheap, and more than anything else, predictable. Which restaurant would you rather own stock in?
Yeah, me too.
You notice I mentioned the three things that make McDonald's successful: tasty (as in, stimulating the taste buds with salt and fat, if not providing a particularly memorable dining experience), cheap, and…predictable.
Human beings are an odd mix of caution and curiosity. This is because we're primates, and we evolved in environments where this blend of traits was highly adaptive.
(Evolution? Oh, don't even get me started. Go to any museum and look at the dinosaur skeletons. Go outside and look down the street. See a crowd fleeing from an oncoming tyrannosaur? 65 million years ago, there were all these gigantic lizards running around, and no people. Now you would be hard-pressed to find even an ankylosaurus on the
The point being that by and large, you (as a primate) learn that this grass here, and grubs under logs and those roots over there are edible and tasty, and so glom them on sight. But every now and then, you come across something like a tree with red fruit. And you go, "Whoa, man, what's that?" Well, it looks really iinteresting. Sniff, sniff, sniff. Lick. But it might be poisonous. Hm. And you're not all that hungry, and Bob's just dug up an anthill…hm. Auntie Maxine's looking interested; let's wait and see if she eats it and drops dead, and meanwhile, here's a new rotted log. Hey, man, ever seen so many grubs in your life?!?
Returning to the modern day, this means that people early on form preferences regarding what they like to read—and they tend to stick to them, only rarely venturing into the dangerous realm of the new when Auntie Maxine hands them a nice, juicy red book and assures them they'll love it.
The result of this, in terms of publishing companies' operations, is that when an editor is faced with the question, "Can we sell it?", the logical corollary is usually—"How much is it like what we already know will sell?"
The answer to that one lies along a spectrum, one end of which is, "Lots. It's like a Grisham, only with a good ending. Or just like Patricia Cornwell, but the people are likable. Or like Danielle Steel, only…" (OK, not going there. [g])—and the other end is, "Well…it really doesn't look like anything I've seen before, let alone anything I've seen on a bestseller list." The closer your book lies to the left-hand end of that spectrum, the higher its chances of being published—because the chances (so far as the publisher is concerned) of its making money are higher. Ergo, the better the chance of the book being bought by an editor.
Bestsellers are not actually bestsellers because they are invariably good books; they're bestsellers because people are in the habit of buying them.
Returning for a moment to my own experience—OUTLANDER was bought by a general fiction editor who loved it (actually, three editors bid on it; she won). She then took it to the first editorial meeting, where she enthused about the book, about how wonderful it was, how they must do something Really Special in terms of cover art, marketing…"Great!" said the marketing people. "What kind of book is it?"
[dead silence for a moment]
"Err…" she said. "I don't really… know…" [long discussion of what it was—no, it's not that—maybe it's…?, no it's really not that, etc., etc.]
Anyway, the upshot was that the publishing company wanted to cancel the three-book contract they'd given me—because they couldn't see any effective way to sell a book that couldn't be described in terms of its genre. My editor, bless her, insisted that they would publish it, and it would (as she's often said) "have to be a word-of-mouth book, because it's too weird to describe to anybody."
(Beyond the weirdness, it was also a Really Long book. Really Long books give publishers Irritable Bowel Syndrome.)
The bottom line here is, yes, you can write (and sell, which is the salient point here) a book that crosses (or obliterates) genres. You can also sell an immensely long book. BUT, if you're going to sell a really unusual book, it also has to be Really Good.
If you have a book that fits well into a tried-and-tested genre, it doesn't have to be the best book ever written in that genre. (Mind, as I said in my first post on this subject, there's certainly not a necessity to write poorly in genre fiction, and it's certainly desirable to write well. It's just that a decently-executed book will still sell.)
Still, on the bright side, the publishing industry has gotten a good deal more flexible in accepting genre-crossing books—because there have been enough of them over the last ten or twenty years that have succeeded. "Paranormal romance," for instance, used to make people's jaws drop, while nowadays, romances featuring vampires (and the occasional werewolf. Oh, I do wish I could remember the title of the romance with the werewolf hero with the retractable penis…) are positively commonplace. Ditto "romantic suspense," which blends mystery and romance. But these genre blends have now become recognizable genres in themselves.
So it all comes down to marketing. A publisher's concern is selling the book. Which means that it first has to be sold to bookstores, and then to the readers. If you go into a bookstore, what's the first thing you do? (beyond glancing at the remainder table or checking to see if they have Godiva milk-chocolate with caramel) You look at the labels on the bookshelves, to guide you to the type of book you're looking for. A book that cannot be easily shelved can't be easily sold to a bookstore—or to a reader.
Which means that a book that crosses or blends multiple genres—if it's special enough to be bought by an editor anyway—is going to be shoved willy-nilly into some genre, just because it has to be shelved. (The default, if the publisher simply can't think what else to do, is to put it in "Fiction." However, conventional bookselling wisdom holds that individual books normally sell better if they can be put into one of the "niche" genres, like romance or mystery, because they show up better.) That being so, the publisher will then orient the cover art and marketing to whatever genre they think will give the book the best chance of selling, whether the book really belongs in that genre (in terms of content) or not.
So the bottom line is, what do you want most? Do you want to write the book of your heart? Or do you want most to be published? (Not rich and famous; nobody can guarantee that—but published.)
If this is a book that just has to be written the way you see it—by all means, write it that way. But if you're crossing genres with abandon just because you feel like it….well, be aware that this likely will make the sale a little harder.