"The very general occurrence of the homosexual in ancient Greece, and its wide occurrence today in some cultures in which such activity is not taboo suggests that the capacity of an individual to respond erotically to any sort of stimulus, whether it is provided by another person of the same or opposite sex, is basic in the species.
Males do not represent two discrete populations, heterosexual and homosexual. The world is not to be divided into sheeps and goats. Not all things are black nor all things white. It is a fundamental of taxonomy that nature rarely deals with discrete categories. Only the human mind invents categories and tries to force facts into separated pigeon-holes. The living world is a continuum in each and every one of its aspects. The sooner we learn this concerning human sexual behavior, the sooner we shall reach a sound understanding of the realities of sex."
Alfred Kinsey