It's more common than you might think. Everyone experiences different sorts of attraction to different genders to *some* degree.

Take myself for example.
I find women of just about every shape and size attractive. In strictly aesthetic terms as well as sexually. And I am comfortable with the idea of romantic relationships with a woman.
I can find men to be aesthetically pleasing, but only sometimes. But I also think men are really sexually attractive, but I have a weird condition that I only find male bodies sexually attractive below the neck! If I so much as glimpse a face, it's an imadiadte 110% turn-off. A sudden reminder of "Ew! Wait, that's a GUY! Gross!" And I could never ever imagine myself in a romantic relationship with another male.