According to a recent Gallup poll:
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.