“It is a rather amazing fact that, of the very many dimensions along which the genital activity of one person can be differentiated from that of another (dimensions that include preference for certain acts, certain zones or sensations, certain physical types, a certain frequency, certain symbolic investments, certain relations of age or power, a certain species, a certain number of participants, and so on) precisely one, the gender of the object choice, emerged from the turn of the century, and has remained, as THE dimension denoted by the now ubiquitous category of 'sexual orientation.”