The media has by now trained us all to say “LGBT" unthinkingly, to take it for granted that Lesbians, Gays, Bisexuals, and the Transgendered are all one harmonious group with the interests of the constituent parts all perfectly aligned with one another. This is bunk. The primary goal of the Lesbians and the Gays is the complete overthrow of what is called heteronormativity, the idea that sexual difference actually matters for anything more than someone's purely private preference. The push for “marriage equality” is the push for the de-sexing of the one institution premised upon the public importance of sexual difference.
Yet, the transgendered rely upon the societal valorization of sexual difference for their identities. A man who really thinks he is a woman wants to be known as a woman in public, wants to be treated as a woman in public, wants, in other words, to inhabit the gender rôle that society has constructed for the other sex. If heteronormativity goes, so does the idea of gender rôles, and if there are no gender rôles, sexual difference does not matter and neither does the quest for a public sexual identity. In sum, the Gays and Lesbians want to scrap the very thing that gives the transgendered any meaning at all. Therefore, the L and G are logically not the allies of the T, but its enemies.