Each genre has certain guidelines of what works and what doesn't, just as each publishing company prints a very specific books. The problem is that as an author you might want to write a book that doesn't fit into neat guidelines.
Does that mean that you can't write that horror romance or conspiracy theory fantasy - uh, no, not exactly. It does mean you might not want to make it your first book. Although guidelines are very inhibiting, they are there for a reason. Publishing companies know what sells and what sells easily. As a first time author, it is difficult to break into the market (i.e. sell to people who you have not met personally). Promoting yourself will be more difficult if you choose to write something that is not standard even if you are publishing it yourself.
I am currently using some beta readers. Since I posted about them and I have a large book I do not want to invest editing money in right now, I wanted to give them a try - more on that in a future post. However, one of the beta readers commented that she generally didn't read Christian Historical Romances because the female characters tend to be... well those ladies you hear who are very happy on the Christian talk radio sessions. Happy, positive, glowing. Yes, they glow through the radio.
I have read a lot of Christian Romances. I agree. I am a rather devout Christian, and I do not identify with most of these women. I would love to glow, but I (as you might have guessed) do not. I think the movies Arachnophobia and Scream are both comedies- members of my family tease me about this. I was rolling on the floor for The War of the Roses (the 1990's version). I loved how she tossed his hand aside in the final scene. I hate slapstick.
But I need to fit into a genre. Could I write a regular romance with all the heaving bosoms? Yeah. However, I do not want to (see devout Christian note above). In fact, I generally skip the sex scenes when I am reading those kind of romances - they bore me. Without those, my options are limited to Avalon (chaste romances, but I have not found any that even mention God) or Christian Romances - inspiring, uplifting. So, the latter is where I best fit in because I don't think God should be taboo in a romance. Is my main character fluffy? A little. But I did give her a little backbone. Call me a rebel.