The sexual revolution of the 1950s and 1960s was based on the ideas of three men: Sigmund Freud, Alfred Kinsey,  and Hugh Hefner, although the doctrines of the sexual revolution ... had their roots in the "free love" movement of Marxism in the 1840s and in Margaret Sanger's writings in the early 20th century. 
Freud claimed that sexual desire could not be controlled or channeled without causing harm to one's psyche. In his model of mental illness, repression would lead to neurosis, because of the dictates of the unconscious mind.
Kinsey applied the techniques of scientific and statistical investigation to human sexuality, ignoring the taboos that previously prevented research in the field. Anonymous surveys showed that what most people considered socially unacceptable sexual practices, including homosexuality and frequent masturbation, were far more common than had been widely believed.
Hefner's "playboy philosophy" was merely a retread of Hedonism, an entirely self-centered pleasure-based life (see also Utilitarianism). What Kinsey did for the science of sex, Hefner did for its popular image - weakening taboos and allowing open discussion.
The sexual revolution gained great traction in the 1960's with the invention of the birth control pill, and in the 1970's with the legalization of abortion, as these helped separate sexual activity from the consequence of pregnancy. With sex now reduced to a low-risk activity, the deterrent against premarital or casual sex and promiscuity was greatly reduced. Sex purely for recreation became possible, without the need for a married family to raise any children produced. This began weakening the social significance of marriage - long-term sexual relationships without the need for marriage became increasingly common.
In response to the sexual revolution, American conservative groups laid policies to restore the lost connection between sex, reproduction and marriage and to set up education programs to reinforce the importance of confining sex to married relationships only. This approach eventually formed what would become abstinence only education.
- Judith A. Reisman, Kinsey: Crimes and Consequences the Red Queen and the Grand Scheme