Americans' views toward a number of moral issues have shifted significantly since 2001. Their acceptance of gay and lesbian relations has increased the most, up 19 percentage points in the past 12 years -- to a record high of 59% today. Americans' tolerance toward having a baby outside of marriage is also now much greater, up 15 points since 2001, to the current 60%.

Americans have also become significantly more accepting of sex between an unmarried man and woman, divorce, embryonic stem cell research, polygamy, and cloning humans. The only issue that Americans have become significantly less accepting of over the last 12 years is medical testing on animals.

These data are from Gallup's annual Values and Beliefs survey, most recently conducted May 2-7. Gallup has asked Americans about their views on many of these issues each May since 2001.

Americans' views of the moral acceptability of 10 of the 19 items Gallup asked about have not changed significantly over time, shifting less than five points since they were first measured.

A majority of Americans continue to say seven of the 19 items measured are morally wrong -- married men and women having an affair, cloning humans, polygamy, suicide, pornography, sex between teenagers (measured for the first time this year), and cloning animals. Attitudes toward two items -- doctor-assisted suicide and abortion -- are fairly evenly split, with less than half of Americans seeing each as either morally acceptable or morally unacceptable.

A majority of Americans see all other items included in the list this year as morally acceptable. Birth control tops the list as the most acceptable, seen as such by 91% of Americans, while having an extramarital affair is the least morally acceptable, at 6%.

One of the interesting features of these trend data is Americans' steady and overwhelming disapprobation of married men and women having an affair, with more than nine in 10 continuing to say this is morally unacceptable, within two points of where it was in 2001. Having an affair thus remains at the bottom of the list of morally acceptable behaviors measured, as it was in 2001.

Implications

Americans have generally become more tolerant of a series of moral behaviors over the past 10-12 years. This trend is particularly evident in views of gay and lesbian relations and having a baby outside of wedlock.

Gay and lesbian relations in particular continue to be at the forefront of the news in the U.S. An increasing number of states have legalized same-sex marriage, and the Supreme Court has several pending decisions on same-sex marriage cases. This resulting increase in awareness of and attention being paid to the gay and lesbian community may be affecting Americans' views.

The change in attitudes toward having a baby outside of marriage may be an instance of attitudes following behavior, given recent Census Bureau data showing the increasing prevalence in American society of children born to mothers who are not married.

More broadly, Americans continue to evince a wide divergence of opinions about the moral acceptability of a number of behaviors. Americans are generally accepting of such things as birth control, divorce, embryonic stem cell research, gambling, sex between unmarried men and women, the death penalty, and having a baby outside of marriage. But they still disapprove of married men and women having an affair, cloning humans, polygamy, suicide, pornography, and teenagers having sex.

Survey Methods
Results for this Gallup poll are based on telephone interviews conducted May 2-7, 2013, with a random sample of 1,535 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, one can say with 95% confidence that the margin of sampling error is ±3 percentage points.

Interviews are conducted with respondents on landline telephones and cellular phones, with interviews conducted in Spanish for respondents who are primarily Spanish-speaking. Each sample of national adults includes a minimum quota of 50% cellphone respondents and 50% landline respondents, with additional minimum quotas by region. Landline telephone numbers are chosen at random among listed telephone numbers. Cellphone numbers are selected using random digit dial methods. Landline respondents are chosen at random within each household on the basis of which member had the most recent birthday.

Samples are weighted to correct for unequal selection probability, nonresponse, and double coverage of landline and cell users in the two sampling frames. They are also weighted to match the national demographics of gender, age, race, Hispanic ethnicity, education, region, population density, and phone status (cellphone only/landline only/both, cellphone mostly, and having an unlisted landline number). Demographic weighting targets are based on the March 2012 Current Population Survey figures for the aged 18 and older U.S. population. Phone status targets are based on the July-December 2011 National Health Interview Survey. Population density targets are based on the 2010 census. All reported margins of sampling error include the computed design effects for weighting.

In addition to sampling error, question wording and practical difficulties in conducting surveys can introduce error or bias into the findings of public opinion polls.