This online test is fairly accurate, for me at least. I started off seriously writing SF, and then diverged into other speculative fiction fields.
You Should Be a Science Fiction Writer
Your ideas are very strange, and people often wonder what planet you're from.
And while you may have some problems being "normal," you'll have no problems writing sci-fi.
Whether it's epic films, important novels, or vivid comics...
Your own little universe could leave an important mark on the world!