Over recent years, polls have shown that Americans are gaining more tolerance for certain controversial moral issues. However, while more and more Americans may be increasing their approval of issues such as stem cell research from human embryos, they are not budging when it comes to their disapproval of adultery. Since 2001, a series of Gallup polls has examined how American views on certain moral issues have changed over time. Back in 2001, three issues earned the morally acceptable nod of approval from only 7 percent of Americans: polygamy, human cloning and married men or women having affairs. In comparison, 13 percent of respondents believed that suicide was morally acceptable, 30 percent felt that pornography was morally acceptable and 31 percent found animal cloning to be morally acceptable. All of the other issues, which included hotly-debated topics such as abortion, same-sex relationships and the death penalty, were deemed morally acceptable by at least 40 percent of Americans. Adultery Slips a Point By 2013, 13 percent of Americans gave the seal of moral approval to human cloning, while 14 percent believed that polygamy was morally acceptable. Most other moral issues included in the poll also gained support between 2001 and 2013. Support for same-sex couples increased from 40 percent to 59 percent, support for human embryo stem cell research increased from 52 percent to 60 percent and support for unwed sex increased from 53 percent to 63 percent. However, the already small percentage of Americans who felt that adultery was morally acceptable decreased from 7 percent to 6 percent. And when you consider that the most widely supported moral issue in the poll (birth control) received support of 91 percent, we find that adultery is not only the most widely condemned moral issue but also the single most unifying issue in the poll. If there\u2019s one thing Americans can agree on, it appears to be marital infidelity. It\u2019s Not Just About Our Conservative Attitudes Toward Sex It is not just about overall American attitudes toward sex, which are generally more conservative than other first world countries. When it comes to other areas of personal sexual choice, American approval rose between 2001 and 2013. The percentage of people who said that pre-marital sex was acceptable rose from 53 percent to 63 percent, and the percentage that said it was morally acceptable to have a baby outside of marriage rose from 45 percent to 60 percent. The difference between adultery and other personal sexual choices may be that adultery involves a clear victim in the form of the betrayed spouse. However, widespread condemnation of adultery in the U.S. does not mean that adultery is a universally controversial issue. A Pew Research study from 2014 found that only 47 percent of French people thought adultery was morally unacceptable. And while the median disapproval rate over 40 countries was much higher\u201478 percent\u2014it still falls short of the number of Americans who consider adultery to be morally wrong. Of course, the fact that adultery is the least-supported moral issue in this poll does not necessarily mean that Americans consider it to be the most serious moral issue with which they must contend. It is likely that many people who oppose the death penalty, for example, or doctor-assisted suicide and also oppose adultery consider the former issues to be the ones with the more critical social implications.