Definition

How many gay people are there?
Sexual Behavior in the Human Male (1948) and Sexual Behavior in the Human Female (1953) reported that: 37% of males and 13% of females had at least some overt homosexual experience to orgasm; 10% of males were more or less exclusively homosexual and 8% of males were exclusively homosexual for at least three years between the ages of 16 and 55. For females, Kinsey reported a range of 2-6% for more or less exclusively homosexual experience/response. 4% of males and 1-3% of females had been exclusively homosexual after the onset of adolescence up to the time of the interview. Kinsey devised a classification scheme to measure sexual orientation. It is commonly known as the Kinsey Scale.

Understanding what Homosexuality is.
Males do not represent two discrete populations, heterosexual and homosexual. The world is not to be divided into sheep and goats. It is a fundamental of taxonomy that nature rarely deals with discrete categories... The living world is a continuum in each and every one of its aspects, (p 639).


While emphasizing the continuity of the gradations between exclusively heterosexual and exclusively homosexual histories, it has seemed desirable to develop some sort of classification which could be based on the relative amounts of heterosexual and homosexual experience or response in each history... An individual may be assigned a position on this scale, for each period in his life.... A seven-point scale comes nearer to showing the many gradations that actually exist, (pp. 639, 656) Kinsey, et al. (1948). Sexual Behavior in the Human Male .


http://www.kinseyinstitute.org/research/