Non-paternity event

In genetic genealogy and clinical genetics, a non-paternity event is when someone who is presumed to be an individual's father is not in fact the biological father. This presumption may be on the part of the individual, the parents, or the physician. Non-paternity may result from sperm donation, undisclosed adoption, intercourse with multiple partners in close succession, as well as medical mistakes, for example, mixups during procedures such as in vitro fertilization and artificial insemination. Where there is uncertainty, the most reliable technique for establishing paternity is genetic testing; however, there is still a risk of error due to the potential for gene mutations or scoring errors.

Overall, the incidence of misattributed paternity ranges from about 2% to 12%, though it may be higher in certain populations. Although rare, the discovery of previously unsuspected or undisclosed non-paternity may have both social and medical consequences. Non-paternity that is due to a previously undisclosed extra-marital relationship often has serious consequences for a marital relationship. Non-paternity is medically relevant when interpreting the results and utility of genetic screening for hereditary illnesses.

Bellis et al. (2005) stated that misattributed paternity "occurs when a child is believed to have been fathered by the husband (or partner) but is actually the progeny of another man." Non-paternity events are also sometimes referred to as misattributed paternity, paternal discrepancy or false paternity. Although it is sometimes referred to as paternity fraud, this suggests that the misattribution was deliberate rather than accidental. In a scientific review of non-paternity studies since the 1950s, Bellis et al. (2005) stated that knowingly covering up an accidental pregnancy that resulted from infidelity is often assumed to be the reason for non-paternity, but that there are many other reasons, "for example, where sex with the long term partner has not produced children a woman might seek conception elsewhere." They said other reasons might be undisclosed adoptions, accidental misattribution resulting from multiple relationships in close succession as well as medical mistakes, such as mixups during procedures such as in vitro fertilization and artificial insemination.

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