Wouldn't it depend on the content of the light novels in question? I assume there are light novels with shounen content, I just don't read them. Or maybe it depends on the publisher, like manga does.

What light novel did you have in mind? Kyou Kara Maou? I'd call that shoujo based on the content (way too many bishounen and BL in-jokes for the shounen genre). Though some series are hard to classify by design, like Escaflowne.