WASHINGTON, D.C. -- The American public has become more tolerant on a number of moral issues, including premarital sex, embryonic stem cell research, and euthanasia. On a list of 19 major moral issues of the day, Americans express levels of moral acceptance that are as high or higher than in the past on 12 of them, a group that also encompasses social mores such as polygamy, having a child out of wedlock, and divorce.

These 19 issues fall into five groups, ranging from highly acceptable to highly unacceptable. Overall, 11 of the 19 are considered morally acceptable by more than half of Americans. Ninety percent of Americans believe birth control is morally acceptable, putting it into the "highly acceptable" category, which has little moral opposition -- the only such issue among the 19. Nine of the other 10 issues with majority acceptance can be put into a "largely acceptable" category, as they have smaller majorities considering them morally acceptable and sizable minorities that consider them morally wrong. Moral agreement with doctor-assisted suicide, though at the majority level this year, is separated from disagreement by fewer than 10 percentage points, and so this issue is considered "contentious."

Solid majorities of Americans consider seven of the issues morally wrong. Four of these -- extramarital affairs, cloning humans, polygamy, and suicide -- are considered morally wrong by more than 70% of Americans and fall into the "highly unacceptable" group. Three other issues fall into the "largely unacceptable" category, as smaller majorities of Americans consider them morally wrong, and at least three in 10 consider them morally acceptable.

Abortion receives neither majority support nor majority disapproval, making it the most contentious issue of the 19 tested. The current split is similar to what Gallup measured last year, but is a more even division than the four prior years when at least half said it was morally wrong.

Gallup has tracked Americans' views on the moral acceptability of 12 of these issues annually since 2001 and the rest annually since 2002 or later. These data are from an overall question asked each year as part of Gallup's Values and Beliefs poll, the latest of which was conducted May 8-11, 2014.

Americans' views on the morality of many of these issues have undergone significant changes over time. For example, acceptance of gay and lesbian relations has swelled from 38% in 2002 to majority support since 2010. Fifty-three percent of Americans in 2001 and 2002 said sex between an unmarried man and woman was morally acceptable, but this year it is among the most widely accepted issues, at 66%. Similarly, fewer than half of Americans in 2002 considered having a baby outside of wedlock morally acceptable, but in the past two years, acceptance has been at or near 60%.

Additionally, a few widely condemned actions, such as polygamy, have become slightly less taboo. Five percent of Americans viewed polygamy as morally acceptable in 2006, but that is now at 14%. The rise could be attributed to polygamist families being the subject of television shows -- with the HBO TV show "Big Love" one example -- thus removing some of the stigma.

Republicans and Democrats Divided on Moral Acceptability of Several Issues

Republicans, independents, and Democrats have differing views of the morality of several issues. Democrats are more likely than Republicans to consider issues like divorce, gambling, medical research using embryos, and having a baby outside of wedlock morally acceptable. But Republicans are more likely than Democrats to see wearing fur, the death penalty, and medical testing on animals as morally acceptable. Independents tend to fall in the middle of the two groups.

In the 12 years Gallup has asked this overall question, Democrats have become significantly more tolerant on many issues, while independents generally show a smaller shift in the same direction and Republicans' views have changed little. The percentage of Democrats who say an issue is morally acceptable has increased for 10 issues, including abortion, sex between an unmarried man and woman, extramarital affairs, cloning humans, divorce, cloning animals, suicide, research using stem cells from human embryos, polygamy, and gay and lesbian relations.

In some cases, the change among Democrats has been substantial. For example, in 2003, 52% of Democrats said having a baby outside of wedlock was morally acceptable, and 40% of Republicans and 61% of independents agreed. This year, 72% of Democrats, a 20-percentage-point increase, say it is morally acceptable. Meanwhile, Republicans have seen no change, with 40% still saying it is morally acceptable, although a higher 50% viewed it as morally acceptable last year. Independents have also not seen a change, with 60% saying having a baby out of wedlock is morally acceptable this year.

Republicans are slightly more accepting of gay and lesbian relations, sex between an unmarried man and woman, and divorce than they were in 2001, when these questions were first asked. Independents' views on the first two issues (but not divorce) also have seen small shifts, but neither group has seen changes as drastic as those among Democrats.

Bottom Line

Americans largely agree about the morality of several issues. Most say birth control is acceptable but that extramarital affairs are wrong. However, other issues show clear, substantial divides. These differences are largely explained by party identification, but previous research has shown that age also plays a factor.

Attitudes about the morality of these behaviors have in many instances changed over the past 13 years, especially among Democrats, and Americans are now more tolerant of issues previously deemed "morally wrong." Some Americans would say this new tolerance is good, because it increases acceptance. The rise of same-sex marriages across the country may be representative of that newfound acceptance. However, others may disagree. In the same poll, 74% of Americans said they thought the state of moral values in the U.S. is getting worse. Furthermore, 6% of Americans said the moral and ethical decline was the country's most important problem in May. Deep divisions exist among Americans, and clashes over the moral acceptance of certain issues will more than likely continue in the years to come.