I've heard it said that writers should only write in one genre. Why? I read and enjoy more than one genre. Why shouldn't I write in more than one? For me (and, I dare say, for most writers) characters and story ideas pop up in my head unexpectedly. I can't help what genre they fall into.
Though I began my writing career with historical fiction and that will probably constitute the bulk of my writing when all's said and done, sometimes the characters who visit my head are not historical. Sometimes they're not even human. Take for example, my newest release, All the Furs and Feathers, the first book in the Cat Tales series. Though the animals in this book are highly anthropomorphized, not a single human is in the story. Nor are any mentioned. For the animals of All the Furs and Feathers, humans don't even exist. Obviously, this is not historical fiction. It's fantasy. Not the epic sort of Lord of the Rings, but the cozy sort. I couldn't anymore banish the characters in it from my head than I could banish those in my historical novels.
So what's yet to come? Definitely more historical fiction. There's one in the works right now and another taking shape in my mind. As for fantasy, there will be more of the Cat Tales series to come, but there may be others as well. A few months ago I awoke from a dream that featured characters I haven't been able to get out of my thoughts ever since. I picture them in period clothing, but they live in a world that does not and never has existed. Fantasy!
The parade of characters that march through my mind on a regular basis range from historical to fantastical to contemporary. So for the moment, historical fiction and cozy fantasy are my focus. What else may come depends upon my cerebral visitors and how insistant they are about their stories being told.