Robert Scott Stewart in Metapsychology:
Despite what we have all heard, married folks in America are actually wildly monogamous. In 2004, only 3.9 % of married men and 3.1% of married women engaged in extramarital sex in the past year (62). The figure that is often heard – that more than half of married men, and a quarter of married women will cheat on their spouses over their lifetime – turns out to be both highly problematic and overestimated. These later figures come from Alfred Kinsey’s studies in the 1950’s, and they are based upon badly unrepresentative samples (46). This was exacerbated by later studies by Shere Hite and Cosmopolitan magazine which placed adultery figures as high as 70% for both men and women. It turns out that in the U.S. only about 20% of men and 10% of women have extramarital sex over their lifetimes (50), although, as Druckerman notes, statistical evidence in this area is strangely hard to come by.
Why there should be such a dramatic difference between reality and perception is interesting. Part of it clearly has to do with the fact that some segments within our society who receive a disproportionate amount of media coverage – such as sports and movie stars, famous politicians and, one wants to add, but probably shouldn’t, evangelical ministers like Jim Bakker, Jimmy Swaggart, and Ted Haggard — do commit adultery in numbers much higher than the norm.