For the past 30 years of the General Social Survey, three out of every four American adults have said that they believe extramarital sex is always wrong, but the number of Americans who report actually having sexual relationships outside their marriage has also held relatively steady, at around 16 percent.
Who is having these affairs has been changing. Since 2000, the age of Americans who cheat has been steadily increasing, according to a study by the Institute for Family Studies.
Starting around 2005, Americans over 55 began reporting rates of extramarital affairs that were about 5 or 6 percentage points higher than those of younger adults. By 2016, 20 percent of older respondents indicated that their marriages were adulterous, compared to 14 percent of people under 55.
Deeper analysis found that the age difference could not be explained by fundamental socio-demographic differences such as race/ethnicity, income level or education.
These numbers are calculated from the survey question item: "Have you ever had sex with someone other than your husband or wife while you were married?"
While most married Americans remain monogamous, the mounting age gap is noteworthy and statistically interesting for a few reasons, said study author Nicholas H. Wolfinger.
Wolfinger, a professor of family and consumer studies and adjunct professor of sociology at the University of Utah, suggests that the spike in sexual affairs may be both a product of age, length of marriage and the culture in which older Americans grew up.
People born between 1940 and 1959 reported the highest rates of extramarital sex ― and are among the first generations to come of age during the sexual revolution. They may have had first-hand experience with 1970s-era experiments with multiple sex partners. And a few people born in the late 1950s may have had swingers for parents, leading them to question taboos surrounding infidelity.
But why have older Americans only become more sexually active outside marriage in recent years? The study suggests that one inducement may have been the proliferation of medications for erectile dysfunction, like Viagra, which only came on the market 20 years ago.
Even as overall divorce rates have fallen in recent decades, there has been an uptick in divorce among the middle-aged.
Wolfinger found that in the older age range, "extramarital sex is most likely to precede the dissolution of a marriage." In other words, the trend is being driven by people in their 50s and 60s ― a time when many of them have been married for between 20 or 30 years. (Once survey respondents enter their 70s, rates of extramarital sex decline considerably.)
One study last year based on national data did show that extramarital sex doesn't raise divorce rates when both spouses are participating. But, as Wolfinger noted, adultery seems to be both a cause and consequence of a failing marriage.