A sample of a thousand American adults found that on average people claimed to tell around 550 lies a year — equivalent to slightly more than one and a half lies a day! But not everyone behaved the same. Nearly a quarter of all the lies were told by just 1 per cent of the people sampled. In other words, the 1 per cent of habitual liars were telling nearly forty lies a day — thought most are likely to be of a rather minor nature. This at least suggests that habitual liars are fairly rare, with most people telling the truth most of the time. In other studies, 92 per cent of people sampled admitted to lying at some point to their romantic partner, while 60 per cent of women and 34 per cent of men said they had lied to obtain sex. Of course, that mighty have been only once over a period of many years, so that the average frequency could be quite low. Nonetheless, it is clear that the temptation is there. Even in experimental games run in the laboratory, people were two to three times more likely to lie if the game was designed so that there was a benefit to be gained from lying. It seems that while most people are fairly honest, a small number of people can’t help themselves, and probably become such habitual liars that they actually come to believe their own lies.
—Robin Dunbar, Friends, Little Brown, 2021