People are much more diverse than that. Our bodies, our personalities, our relationships, our sexualities are so much more diverse than that. Our laws and public policies must accept this. Nate Charest looks at this more at dailynexus.com...
Fundamentally, our society seems to have created several spectrums with which to quantify sexual preference. There is a spectrum along the sex line — whether one prefers a penis or vagina. Another spectrum exists along the gender line — this is harder to define, but slides from typically masculine behavioral traits to typically feminine behavioral traits. A third spectrum spans between what is considered “vanilla sex” and “kinky sex” — this covers a vast variety of possible “kinks,” but fundamentally hinges on the sex act itself. A fourth spectrum captures the idea of monoamory (literally ‘one love’) versus polyamory (literally ‘many loves’) — though this spectrum, perhaps, can be represented as a simple binary preference.While it is convenient to start with "monoamory vs. polyamory," there is much diversity under the label of polymory.
The sex preference is a biological and social imperative about what a person has sex with.Of course there are others, too, such as whether someone is attracted to younger adults or older adults or only someone around their own age, whether someone tends to be racially endogamous in their attraction, as most people are, exogamous, or hyperendogamous (preferring a consanguinamorous relationship above all others.)
The gender spectrum is a personality-based preference about with whom a person has sex.
The kink preference is about how a person has sex.
The poly/monoamory is about how many people the person allocates emotion to.
Charest has the point that while, say, a monogamist gay man is not in the same "sexual minority" category as a polyamorous heterosexual woman, adults who are sexual minorities should have solidarity in seeking equality for all adults.
A comment from Thomas Leavitt adds:
http://www.bisexual.org/kleingrid.html