Alfred C Kinsey: a public/private life by James H Jones W W Norton, pounds 28; A pompous, pedantic don from the Mid-West transformed the landscape of desire, argues Richard Davenport-Hines
Jewel Jones my grandmother (deceased) assured me that I could accomplish almost anything if only I had enough `little Willie'," declares James Jones in the acknowledgments to his gigantic biography of American sexologist Alfred Kinsey (1894-1956). It is a timely reminder that with sex, you've just got to laugh. People who treat it too solemnly make fools of themselves, as Jones takes 934 pages to show.

His biography is packed with undignified sexual anecdotes that have offended Kinsey's admirers. Later chapters recount naive, sometimes fatuous experiments by Kinsey and his colleagues in wife-swapping and sexy movies. These transgressions seem too humourless ever to have been raunchy. Nor are Kinsey's eccentricities very startling. Pioneers of sex research are as likely to have unconventional sexual outlets as pioneer child psychotherapists are certain to behave like bad children.

Jones's real offence is to have written about a driven, introverted intellectual born in the 19th century with all the cuddly reductive judgmentalism of Esther Rantzen. "Kinsey's reluctance to talk about his private life" is treated as an emotional disability rather than as reticent good manners. He was too busy with his adult career to visit his brother or sister - which prompts Jones, who clearly relishes extrovert family re-unions, to sniff "something in Kinsey would not allow him to reach out". His distance from siblings must mean that "there was simply too much pain". Can't it just be that they were bores?

Despite his sexual buffoonery, Kinsey was important in the history of 20th-century ideas. In the 1940s, he pioneered those surveys of people's sexual acts, desires and affections which have since proliferated. Undeniably they have been a force for good, reducing the possibilities of sexual ignorance and oppression, though never achieving the impossible by eliminating the dissatisfaction and unhappiness that sex can arouse.

Such surveys are silliest when undertaken by researchers like Shere Hite who, cloaked in the mantle of science and crouching behind a battery of statistics, encourage self-centred, histrionic people to make fashion statements about their sexuality. The Hite reports on male and female sexuality are merely Masters and Johnson with a dab of CK1 behind the labia.

Kinsey, however, mounted a ferocious attack on the patriarchal institutions of the early 20th century. It has been harder to maintain old prejudices, masquerading as ethical values, since his demonstration that significant numbers of people felt or behaved differently from conventional pretences. Society rewards or punishes individuals not for what they do, but for how their acts are defined; and since Kinsey, westerners have more than ever been devoted to better justifying themselves rather than in better behaving.

Sex surveys may strengthen some people in personal myths, but can also be gloriously destructive of the corrupt fantasies of power politics. The National Survey of Sexual Attitudes and Lifestyles, initiated by the Department of Health in 1987 as a response to HIV, was halted in 1989 by Margaret Thatcher because she claimed that it invaded privacy and was likely to produce unreliable results. In truth, of course, she was scared.

Her fears were justified. Contrary to the Conservatives' demonisation of the Swinging Sixties' promiscuity, the survey (completed with Wellcome Foundation finance) found no evidence of a sexual revolution then. The steepest fall in age at first intercourse was in the 1950s, for example; thus technological advances like the oral contraceptive were a response to and not a cause of changed behaviour. Perhaps John Major knew this, and his nostalgia for the "warm beer" of the 1950s was a coded promise of hot sex.

Kinsey himself, after research at Harvard, was appointed in 1920 to the zoology department of Indiana University. He spent the rest of his life based in the remote, picturesque university town of Bloomington. His speciality was the taxonomy of gall wasps. As a scientist he was idealistic, systematic and zealous, with a touchingly infectious enthusiasm for his own work.

His private desires, however, were less orderly than his intellect. Though the publisher's promotional material trumpets that Jones takes Kinsey "out of the closet", the stress on Kinsey's homosexuality is exaggerated. Instead, as Jones shows in sumptuous detail, Kinsey was a dedicated wanker, eventually very proud of proving - contrary to the medical consensus - that most men dribble rather than spurt. Jones even quotes some poor old pensioner living in Kinsey's boyhood home who, in the 1970s, found a cleft in the planks of his attic, rashly thrust his hand in and withdrew a gruesome old brush which had been Kinsey's favourite appendage in elaborate rituals of auto-eroticism some 60 years earlier.

Initially, Kinsey failed to consummate his marriage. Instead, he spent his honeymoon climbing mountains with his bride and, as Jones solemnly notes, teaching her how to handle snakes. Eventually he fathered four children. The marriage was impressively resilient, and both partners showed the flexibility in adjusting to each other's wishes that shows the maturest loving respect.

In the early 1930s, Kinsey began talking more obtrusively about sex to colleagues. He became mildly exhibitionistic, and masturbated openly. He meddled in the lives of students. "He was a dirty old man," one woman told Jones. "He really hurt us. We were just kids from Mississippi. We didn't know anything." But he was saved from sordid futility when students began agitating for compulsory syphilis testing on campus. As a result of this hysteria, Kinsey began to teach a sex education course in 1938.

This course, with its accompanying counselling, was a huge success. Kinsey attacked repressive moralities by enlisting apparently neutral scientific terminology to demystify sex. His advice was sympathetic, impersonal and constructive. Struck by the lack of readable data on sexual conduct, he issued questionnaires to his students on their erotic histories. In 1939 he took his first field-trip, visiting Chicago to interview the young men of a visibly gay neighbourhood. In this period he started having anonymous, clandestine sexual contacts with other men.

With the support of the Rockefeller and other foundations, Kinsey conducted nation-wide interviews on erotic experience and published the results in Sexual Behaviour in the Human Male (1948) and Sexual Behaviour in the Human Female (1953). Though one can quibble over details, his observations were acute, humane, fearless and provocative. By studying sexual intercourse simply as an "outlet" he avoided sentimentalisation or sanctification. His stress on orgasm as the measure of achievement has informed sexual discourse ever since. His data on the prevalence of homosexuality reformed attitudes, though recently his figures have been challenged.

Kinsey's findings on female sexuality were even more influential. Women had hitherto been bombarded with the messages of submission encapsulated in the title of Dr Marie Robinson's The Power of Surrender, a genteel sex-guide which sold over a million copies. But Kinsey's research has broadened our sexual repertoire. To take one example, franker sexual discussion since the 1950s has contributed to the increasing substitution of oral for penetrative sex. It is experienced by a rising number of young people who have not already had vaginal intercourse. Among older people, oral- genital contact largely followed experiences of penetrative sex.

Over three-quarters of men and women aged 18-24 in the late 1980s reported non-penetrative sex in the last year to Britain's Wellcome survey. But older generations who might have been expected to have used non-penetrative sex to avoid pregnancy reported a much lower incidence of it when young.

Kinsey's most effective opponent was the critic Lionel Trilling, who complained that the reports were an attempt by statistical science to reassure people that solitude was imaginary and physical contact more than a consolation. Another apt objection is that much of Kinsey's research was conducted in war-time, when people under the threat of death grow untypically amorous. His factual data particularly damaged Freudian and Kleinian theory, and its analysts. They responded with virulent attacks.

The publicity surrounding Kinsey's reports was huge. Guy Burgess, who imported one of the first copies to Britain in 1948, was so frightened of it being stolen that he hid it where he thought no-one else would look - in the Foreign Secretary's in-tray. The Home Office, felt so threatened that in 1953 it considered prosecuting Sexual Behaviour in the Human Female for obscenity. "The worst passage" was identified as a statement that venereal diseases were curable by antibiotics. "Fear of disease is perhaps the most potent factor in restraining young people from promiscuous immorality," minuted an expert. It was this bogus morality - enforced by guilt, ignorance, bans and scapegoats - that Kinsey helped to break.