Accurately assessing people's sexual behavior is difficult, since strong social and personal motivations occur, depending on social sanctions and taboos, for either minimizing or exaggerating reported sexual activity.
American experiments in 1978 and 1982 found the great majority of men were willing to have sex with women they did not know, of average attractiveness, who propositioned them. No woman, by contrast, agreed to such propositions from men of average attractiveness. While men were in general comfortable with the requests, regardless of their willingness ("Why do we have to wait until tonight?", "[I'm sorry], I'm married"), women responded with shock and disgust ("You've got to be kidding", "What is wrong with you? Leave me alone").
The number of sexual partners people have had in their lifetimes varies widely within a population. A 2007 nationwide survey in the United States found the median number of female sexual partners reported by men was seven and the median number of male partners reported by women was four. The men possibly exaggerated their reported number of partners, women reported a number lower than the actual number, or a minority of women had a sufficiently larger number than most other women to create a mean significantly higher than the median, or all of the above (see Pareto principle). About 29% of men and 9% of women reported to have had more than 15 sexual partners in their lifetimes. Studies of the spread of sexually transmitted diseases consistently demonstrate a small percentage of the studied population has more partners than the average man or woman, and a smaller number of people have fewer than the statistical average. An important question in the epidemiology of sexually transmitted infections is whether or not these groups copulate mostly at random (with sexual partners from throughout a population) or within their social groups (assortative mixing).
A 2006 systematic review (analyzing data from 59 countries worldwide) found no association between regional sexual behavior tendencies, such as number of sexual partners, and sexual-health status. Much more predictive of sexual-health status are socioeconomic factors like poverty and mobility. Other studies have suggested that people with multiple casual sex partners are more likely to be diagnosed with sexually transmitted infections.
Severe and impulsive promiscuity, along with a compulsive urge to engage in illicit sex with attached individuals is a common symptom of borderline personality disorder, histrionic personality disorder and antisocial personality disorder but most promiscuous individuals do not have these disorders.
In 2008, a U.S. university study of international promiscuity found that Finns have had the largest number of sex partners in the industrialized world, and British people have the largest number among big western industrial nations. The study measured one-night stands, attitudes to casual sex, and number of sexual partners. A 2014 nationwide survey in the United Kingdom named Liverpool the country's most promiscuous city.
Britain's position on the international index "may be linked to increasing social acceptance of promiscuity among women as well as men". Britain’s ranking was "ascribed to factors such as the decline of religious scruples about extramarital sex, the growth of equal pay and equal rights for women and a highly sexualised popular culture".
The top-10-ranking OECD nations with a population over 10 million on the study's promiscuity index, in descending order, were the United Kingdom, Germany, the Netherlands, the Czech Republic, Australia, the United States, France, Turkey, Mexico, and Canada.
A nonscientific survey conducted in 2007 by condom-maker Durex measured promiscuity by a total number of sexual partners. The survey found Austrian men had the highest number of sex partners of males globally with 29.3 sexual partners on average. New Zealand women had the highest number of sex partners for females in the world with an average of 20.4 sexual partners. In all of the countries surveyed, except New Zealand, men reported more sexual partners than women.
One review found the people from developed Western countries had more sex partners than people from developing countries in general, while the rate of STIs was higher in developing countries.
According to the 2005 Global Sex Survey by Durex, people have had on average nine sexual partners, the most in Turkey (14.5) and Australia (13.3), and the least in India (3) and China (3.1).
A 1994 study in the United States, which looked at the number of sexual partners in a lifetime, found 20% of heterosexual men had only one partner, 55% had two to 20 partners, and 25% had more than 20 partners. More recent studies have reported similar numbers.
A 1989 study found a very high number of partners (over 100) to be present though rare among homosexual males. General Social Survey data indicates that the distribution of partner numbers among men who have sex exclusively with men and men who have sex exclusively with women is similar, but that differences appear in the proportion of those with very high number of partners, which is larger among gay men, but that in any case makes up a small minority for both groups. OkCupid discovered a similar pattern in the data collected from its vast number of users, published in 2010: the median number of self-reported lifetime sexual partners for both gay and straight men was six; however, a small minority of gay men (2%) were having a disproportionate share of all self-reported gay sex (23%). According to updated OkCupid data published in 2014, gay male users self-reported a lower median of lifetime sex partners than straight male users: four for gay men and five for straight men. A 2007 study reported that two large population surveys found "the majority of gay men had similar numbers of unprotected sexual partners annually as straight men and women."
The words 'womanizer', 'playboy', 'stud', 'player', 'ladies' man', 'lady killer', and 'rake' may be used in reference to a man who has romantic affairs or sexual relations, or both, with women, and who will not be monogamous. The names of real and fictional seducers have become eponymous for such promiscuous men. The most famous include Lord Byron, , Errol Flynn, Warren Beatty, Hugh Hefner, Wilt Chamberlain, Gene Simmons, Howard Hughes, and the historical Giacomo Casanova (1725–98). Others include Elvis Presley, Frank Sinatra, Dean Martin, and Steve McQueen. Famous historical fictional seducers include Don Juan, who first appeared in the 17th century, the fictional Vicomte de Valmont from Choderlos de Laclos's 18th-century novel Les Liaisons Dangereuses (Dangerous Liaisons), and Lothario from Nicholas Rowe's 1703 play The Fair Penitent. More recent fictional characters who can be considered womanizers include Tony Soprano, James Bond, Chuck Bass, James T. Kirk, Tony Stark, Glenn Quagmire, Joe Quimby, Bruce Wayne, Charlie Harper, Sam Malone, Joey Tribbiani, Popeye Doyle, Donald Draper, Hank Moody, Fonzie, Barney Stinson, Tim Riggins and Drake Parker.
During the English Restoration period (1660–88), the term 'rake' was used glamorously: the Restoration rake is a carefree, witty, sexually irresistible aristocrat typified by Charles II's courtiers, the Earl of Rochester and the Earl of Dorset, who combined riotous living with intellectual pursuits and patronage of the arts. The Restoration rake is celebrated in the Restoration comedy of the 1660s and the 1670s. After the reign of Charles II, and especially after the Glorious Revolution of 1688, the rake was perceived negatively and became the butt of moralistic tales in which his typical fate was debtor's prison, permanent venereal disease, and, in the case of William Hogarth's A Rake's Progress, syphilis-induced insanity and internment in Bedlam.
Empress Catherine II
is remembered in popular culture for her sexual promiscuity.
In 1994, a study in the United States found almost all married heterosexual women reported having sexual contact only with their husbands, and unmarried women almost always reported having no more than one sexual partner in the past three months. Lesbians who had a long-term partner reported having fewer outside partners than heterosexual women. More recent research, however, contradicts the assertion that heterosexual women are largely monogamous. A 2002 study estimated that 45% to 55% of married heterosexual women engage in sexual relationships outside of their marriage. While the estimates for heterosexual males in the same study were greater (50–60%), the data indicate a significant portion of married heterosexual women have or have had sexual partners other than their spouse, as well.
Since at least 1450, the word 'slut' has been used, often pejoratively, to describe a sexually promiscuous woman. In and before the Elizabethan and Jacobean eras, terms like "strumpet" and "whore" were used to describe women deemed promiscuous, as seen, for example, in John Webster's 1612 play The White Devil.
Thornhill and Gangestad found that women are much more likely to sexually fantasize about and be attracted to during the fertile phase of the menstrual cycle than the luteal phase (see Ovulatory shift hypothesis), whereas attraction to the primary partner does not change depending on the menstrual cycle. A 2004 study by Pillsworth, Hasselton and Buss contradicted this, finding greater in-pair sexual attraction during this phase and no increase in attraction to extra-pair men.