France’s penchant for infidelity is notorious – and quantifiable. In a 2013 study by the Pew Research Centre just 47% of French respondents thought extramarital affairs were morally unacceptable, the lowest proportion in the world. The unforgiving United States, with 84%, was closer to the pious Muslim and Catholic countries at the top of the scale.

The French Institute of Public Opinion ( IFOP ) has conducted extensive research on the matter. It has found that Italians are actually the worst offenders, with 47% of men admitting to unfaithful sex. Phlegmatic Britons are least likely to have engaged in “un jeu de séduction”.

IFOP has been tracking infidelity in France since 1970. In that time the share of adults who confess to having cheated has more than doubled, from less than a sixth to more than a third. Recent polls have provided a wealth of detail. Adulterers are most likely to two-time with random acquaintances, though 8% have done so with a member of their partner’s family. Some 42% have used a car for their tryst, slightly more than have dabbled in their own residence. Remarkably, one in eight French people believes that regular sex outside of a relationship does not count as infidelity. Women generally have stricter definitions of cheating than men, with the exception of fantasising – which men clearly feel guiltier about.

Not all French people are equally susceptible. Gay men are nearly three times as likely to have been unfaithful to their current partner as straight men. Among practising Catholics, 48% have sinned, compared to 38% of lapsed believers. Older and wealthier people report higher rates of infidelity, though that may be due to the length of their relationships. Cheaters are also more likely to be overweight and less likely to be satisfied with their sex lives. Though France is permissive of affairs, they seem like a poor recipe for happiness.

ILLUSTRATION DONOUGH O’MALLEY