These studies report that about 12–26% of married women and 15–43% of married men engage in extramarital sex.
The only way to get scientifically reliable estimates of extramarital sex is to use nationally representative samples.
This can be interpreted as a form of plural mating, as are those societies dominated by female-headed families in the Caribbean, Mauritius and Brazil where there is frequent rotation of unmarried partners.
In all, these account for 16 to 24% of the "monogamous" category.
Bronze sculpture of an elderly Kashubian married couple located in Kaszubski square, Gdynia, Poland, which commemorates their monogamous fidelity, through the time of their separation, while he temporarily worked in the United States.
That study was funded by the National Institute of Mental Health.
A majority of married people remain sexually monogamous during their marriages.
The number of married partners who engage in extramarital sex never exceeds 50% in studies using large or nationally representative samples.
These findings support the claim that the reported amount of extramarital sex differs across cultures and across genders.
Recent surveys conducted in non-Western nations have also found cultural and gender differences in extramarital sex.
The prevalence of sexual monogamy can be roughly estimated as the percentage of married people who do not engage in extramarital sex.