After we finish writing our books, no matter the type of book or genre the book fits into, or how long or short it is, we need to figure out who is the target audience of the story. That way, when we market, we get an idea of who to market to, and if we're looking for a publisher, agent or editor, we also know who we're marketing it to.
It is not always easy to say my target audience is one gender over another, or if it's a specific age group (unless we're writing children's books or erotica for a targeted 'adult' audience).
One thing I have learned, though, is even when we think we know who will be reading (or hope to have read) our work, sometimes, it is not always so cut and dry. I, personally, read anything, well, anything that is well-written, and I will enjoy that, not just as a reviewer, but as one who also reads books (yes, print copy of books) for research, or just entertainment. Everything from biographies to self-help books, to the classics (and much, much more). In my writing, I have asked others to read some of my stories, not just females within a certain age group, but males as well. I find I get different perspectives of the type of stories based on the gender of the reader, as well as the age of the reader, and I take all comments (positive and negative) into consideration.
So, if you know your target audience, find some readers who don't "fit" in that audience and see what they say. You may be limiting your promotion and marketing to readers where there are so many other demographics out there. Never limit yourself or your writing. Also, pursue those readers who may be just waiting to find a book such as yours (or mine).