As Nietzsche noted, "[O]nly that which has no history is definable" ([1887] 1968, p. 516). This observation is clearly supported by the dramatic changes in the ways in which sexual orientation has been conceptualized over the last quarter century and, in particular, the last decade. As a result, the concept of sexual orientation may be difficult to define with any assurance of general agreement. It is currently mired, and surely will continue to be mired, in conflicting interpretations of the history of the behaviors that are assumed to be the expression of specific sexual orientations. The question of sexual orientation remains a conceptual battleground where many of the most critical issues regarding the nature of human sexuality, if not the human condition itself, are debated.

Sexual orientation generally can be described as the integration of the ways in which individuals experience the intersection of sexual desires and available...