The answer is that I am writing what I enjoy reading. My first book was in the women's fiction genre. It wasn't my best piece of work. I had only written short stories previously and all of them had been in the crime/thriller or horror genre.
So why did I turn to women's fiction for my first novel? I suppose I thought it would be easier. Very ignorant of me, I know. The writing was a hard slog. I wrote for two years', had a two year break, then wrote for another year until it was finally finished. I hated every second I worked on that book.
I then took a break. I wrote short stories, articles and a couple of non-fiction books - anything to stop me thinking about writing another novel-length piece again. During this time, I was also reading a lot - as I always have. My favourite author's include Stephen King, Mo Hayder, Michael Connelly, Gillian Flynn... You can see the pattern here. It was reading a Stephen King novel at the age of twelve that made me want to be a writer in the first place.
I asked myself why I like reading in these genres. Why do I love to immerse myself in world's occupied by serial killers, stalkers, monsters and the odd killer clown? It's because I'm interested in the dark side of human behaviour. I want to know what makes the killer tick and what dark choices humans make to survive. THIS is what I should be writing about!
And now, I am. My new wip includes a serial killer, a stalker and a DI who also has a dark side. And I'm loving it.
Even my short stories always seem to have a murder or crime involved. I tried writing a story for The People's Friend a while back, but no matter how hard I tried, I couldn't stop myself writing a murder and arson attack into the plot. At least I tried!
Changing genre has been the best thing I have ever done. It has made me fall in love with writing again.