Can I elaborate without voting?
After a bit of self-study I've got to the conclusion that it's just not that simple. With respect to sex as a physical act for pleasure, I'm more or less bisexual, although the idea of male homosexuality doesn't normally turn me on very much.
However, with respect to sex as the ultimate form of intimacy I'm pretty thoroughly heterosexual. Since I'm anatomically male that means having a female partner; however, I'd really prefer to be anatomically female, and if I were, I'm pretty sure I'd switch to preferring men. Then again, at the moment my relationship with my wife, including the ability to occasionally go beyond cuddling, is more important to me than having my body match my image of what it should be like. Still, while it's better intimacy-wise to consider the thing between my legs as my penis, from the point of view of actually getting an orgasm it's much more effective to think of it as a strap-on.
Considering all this, I'm pretty much of the opinion that concepts like gender identity, sex, and sexual orientation are pretty hard to define. But then, we all knew that.
Nfr