This article begins by proposing, on the basis of the double status of “theory” in Freud, which allows us to distinguish between the dimensions of “metapsychology” and “infantile sexual theories”, a way to reread the discussions around the “dialectic of desire” that Lacan developed in the 50s and particularly in his seminars The Object Relation and Formations of the Unconscious. He articulated this latter dimension in an original way, extending it to the whole of the Oedipus and the sexuation that concludes it, first on the example of “masculine” identification. We will then argue that it is also possible to conceive of “feminine” identification, within the same conceptual framework, starting from “early sexual theories” as reported by Melanie Klein concerning the Oedipus complex of the girl, to finally demonstrate that this “generalized dialectic of desire”, which will serve us as a heuristic tool in our psychoanalytical reflections on sexual diversity, entails three theoretical consequences that could be described as “inclusive”: dissociation of maternal and paternal functions from the difference of sexes, bisexuality or even the essential plurality of sexual identity and sexual object choice, and the immanent possibility of transsexual identity.