Asexuality (also known as nonsexuality), in its broadest sense, is the lack of sexual attraction or the lack of interest in and desire for sex. Sometimes, it is considered a lack of a sexual orientation. One commonly cited study placed the incidence rate of asexuality at 1%.
Asexuality is distinct from abstention from sexual activity and from celibacy, which are behavioral and the latter is usually for a religious reason. A sexual orientation, unlike a behavior, is definitionally "enduring". Some asexuals do have sex, despite lacking a desire for it.
In the mid-twentieth century, Alfred Kinsey rated individuals from 0 to 6 according to their sexual orientation from heterosexual to homosexual. He also included a category he called "X" for individuals with "no socio-sexual contacts or reactions". He labeled 1.5% of the adult male population as X. In Kinsey's second book, Sexual Behavior in the Human Female, he reported this breakdown of individuals who are X: unmarried females = 14–19%, married females = 1–3%, previously married females = 5–8%, unmarried males = 3–4%, married males = 0%, and previously married males = 1–2%.