Story Highlights Adultery remains least morally acceptable to Americans

Most still frown on polygamy, human cloning and suicide

Over past 15 years, increase in support for all but adultery

WASHINGTON, D.C. -- While a select few actions remain deeply taboo for much of the country, there has been an increasing shift to moral acceptability for some of these over time. Such actions include suicide (which 19% of Americans call "morally acceptable"), polygamy (16%) and cloning humans (15%). On the other hand, "married men and women having an affair" has remained at the bottom of a list of 19 moral behaviors Gallup has measured, with only 8% considering it morally acceptable.

These results come from the May 6-10 Gallup Values and Beliefs poll. Since 2001, this annual poll has gauged the nation's moral sensibilities across numerous behaviors or social issues, including divisive or sensitive topics such as having children out of wedlock, premarital sex, gay or lesbian relations and abortion. Many of the 19 topics rated this year are now judged as morally acceptable by record or near-record percentages of U.S. adults, in tandem with a rising wave of social liberalism.

To some extent, these changing social mores have affected even behaviors that a vast majority of the country routinely judges as "morally wrong." Since 2003, the proportion of U.S. adults saying polygamy is morally acceptable has increased by nine percentage points. Since 2001, cloning humans has seen an increase of eight points; and suicide, a six-point gain. Still, each of these items retains its essence of moral repugnancy in the nation's social consciousness, as resounding majorities describe each of these behaviors as morally wrong.

Even among these taboo topics, married men and women engaging in an affair occupies its own space, in terms of public contempt. Over the past 15 years, no more than one in 10 U.S. adults have ever judged extramarital trysts as moral. This item has always ranked at the bottom of all issues tested in terms of moral acceptability, though at times in previous years it tied cloning humans or polygamy. In contrast to the continued, nearly universal condemnation of adultery, other topics regarding marriage and who should be having sex with whom have changed remarkably: divorce, sex between an unmarried heterosexual couple, and gay/lesbian relations have all seen double-digit increases in the percentage saying they are morally acceptable.

Older Americans Find More Issues Highly Unacceptable

Gallup has previously defined moral issues as being highly unacceptable when 20% or less of U.S. adults rate them as morally acceptable, which would include suicide, cloning humans, polygamy and adultery in this year's poll.

There is variation in acceptability by age groups. In particular, those aged 65 or older find a wider set of issues as morally beyond the pale: In addition to the four items examined above, U.S. seniors give low moral acceptability scores to pornography (18%) and sex between teenagers (18%). In contrast, young Americans have a more tolerant outlook: there is only one issue -- extramarital affairs -- that less than 20% of 18- to 29-year-olds rate as morally acceptable.

Bottom Line

Americans today appear to have greater comfort with a host of issues or behaviors that were at one time subject to social stigma. And even among the most taboo behaviors, there is evidence of changing moral judgments, at least in relation to suicide, cloning humans and polygamy.

Why these items are seeing a modest improvement on their perceived morality is hard to determine, though the disproportionately high share of 18- to 29-year-olds labeling them as acceptable may be both telling and predictive. Young adults find just one behavior -- affairs between married men and women -- highly unacceptable. Provided younger Americans do not shift toward a more culturally conservative stance as they age -- and there is reason to believe they won't, given the increasingly liberal views of older Americans -- fewer behaviors may eventually be seen as taboo.

But the nation's thoughts on extramarital affairs may be considered an island of stability amid this sea change. Even as much of the country expands the institution of marriage to include gay and lesbian couples, there has been no redefining of the commitment a couple enters into when they get married.

Survey Methods

Results for this Gallup poll are based on telephone interviews conducted May 6-10, 2015, with a random sample of 1,024 adults, aged 18 and older, living in all 50 U.S. states and the District of Columbia. For results based on the total sample of national adults, the margin of sampling error is ±4 percentage points at the 95% confidence level. All reported margins of sampling error include computed design effects for weighting.

Each sample of national adults includes a minimum quota of 50% cellphone respondents and 50% landline respondents, with additional minimum quotas by time zone within region. Landline and cellular telephone numbers are selected using random-digit-dial methods.

Learn more about how Gallup Poll Social Series works.