One measure of infidelity is covert illegitimacy, a situation which arises when someone who is presumed to be a child's father (or mother) is in fact not the biological parent.
Frequencies as high as 30% are sometimes assumed in the media, but research Such studies show that covert illegitimacy is in fact less than 10% among the sampled African populations, less than 5% among the sampled Native American and Polynesian populations, less than 2% of the sampled Middle Eastern population, and generally 1–2% among European samples.
These differences have been generally thought due to evolutionary pressures that motivate men towards sexual opportunity and women towards commitment to one partner.
In addition, recent research finds that differences in gender may possibly be explained by other mechanisms including power and sensations seeking.
In general, national surveys conducted in the early 1990s reported that between 15–25% of married Americans reported having extramarital affairs.
People who had stronger sexual interests, more permissive sexual values, lower subjective satisfaction with their partner, weaker network ties to their partner, and greater sexual opportunities were more likely to be unfaithful.
Infidelity (synonyms include: cheating, adultery (when married), netorare (NTR), being unfaithful, or having an affair) is a violation of a couple's assumed or stated contract regarding emotional and/or sexual exclusivity.
Other scholars define infidelity as a violation according to the subjective feeling that one's partner has violated a set of rules or relationship norms; this violation results in feelings of sexual jealousy and rivalry.
Studies show that 90% of cheaters are men, with the remaining 10% women.According to The New York Times, the most consistent data on infidelity comes from the University of Chicago's General Social Survey (GSS).Interviews with people in non-monogamous relationships since 1972 by the GSS have shown that approximately 12% of men and 7% of women admit to having had an extramarital relationship.In marital relationships, exclusivity expectations are commonly assumed, although they are not always met.When they are not met, research has found that psychological damage can occur, including feelings of rage and betrayal, lowering of sexual and personal confidence, and damage to self-image.