Non-paternity event

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Non-paternity event is a term in genetic genealogy and clinical genetics to describe the case where the biological father of a child is someone other than who it is presumed to be. The presumption may be either on the part of the presumed father or by the physician. Non-paternity may result from a number of different scenarios: it may arise from sperm donation or when the mother had sexual intercourse with a man other than the presumed father. Other than the situation of egg donation, the identity of a child's mother is seldom in doubt.

Non-paternity (and non-maternity) may also result from hidden adoptions: that is, when a child is never told he or she was adopted. Where there is uncertainty, then the only definitive diagnosis of non-paternity is from DNA testing.

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 will have obvious consequences for the marital relationship which it violates. Non-paternity is medically relevant when interpreting the results and utility of genetic screening for hereditary illnesses such as cystic fibrosis.

In genetic genealogy the term NPE is often used in a wider context to indicate a break in the link with the Y-chromosome and the surname. Such a breakage may occur because of illegitimacy, the use of an alias, or a deliberate change of surname.


Rates of non-paternity

The rate of non-paternity is commonly quoted to be around 10%.[1][2]

However, a 2005 scientific review of international published studies of paternal discrepancy found a range in incidence from 0.8% to 30% (median 3.7%), suggesting that the widely quoted figure of 10% of non-paternal events is an overestimate. In situations where disputed parentage was the reason for the paternity testing, there were higher levels; an incidence of 17% to 33% (median of 26.9%). Most at risk of parental discrepancy were those born to younger parents, to unmarried couples and those of lower socio-economic status, or from certain cultural groups.[3]

A 2006 study examined non-paternity rates from 67 published studies. Non-paternity rates for men who were judged to have high paternity confidence ranged from 1.9% in the U.S. and Canada, 1.6% in Europe, and 2.9% elsewhere. In contrast, men in studies of disputed paternity, considered to have low paternity confidence, the rates of non-paternity were higher – 29% in the U.S. and Canada, 29% in Europe, and 30% elsewhere.[4]

The rate of non-paternity varies according to the population studied:

  • Mexico: 9.8% to 13.8% in a sample of 396 children.[5]
  • Switzerland: 0.3% to 1.3%.[6]
  • United Kingdom: 1 to 2% in a sample of 1,678 men.[7]
  • United States: A study in Michigan of 1417 white and 523 black children found non-paternity rates of 1.4% and 10.1% respectively.[8][9][10][11]


  1. Neale MC, Neale BM, Sullivan PF. Nonpaternity in linkage studies of extremely discordant sib pairs. Am J Hum Genet, 2002, volume 70, issue 2, pp526-529.
  2. Rincon P. Study debunks illegitimacy 'myth'. BBC News, 11 February 2009.
  3. Bellis MA, Hughes K, Hughes S, Ashton JR. Measuring paternal discrepancy and its public health consequences. Journal of Epidemiology and Community Health. September 2005; 59, 9: 749–54.
  4. Anderson, K. G. (2006) Evidence from Worldwide Nonpaternity Rates. Current Anthropology, 47, 3 pp. 513-520.
  5. Cerda-Flores RM, Barton SA, Marty-Gonzalez LF, Rivas F, Chakraborty R. Estimation of nonpaternity in the Mexican population of Nuevo Leon: A validation study with blood group markers. Am J Physical Anthropol, 1999, volume 109, issue 3, pp281-293.
  6. Sasse G, Müller H, Chakraborty R, Ott J. Estimating the frequency of nonpaternity in Switzerland. Hum Hered, 1994, volume 44, issue=6, pp337-343.
  7. King TE and Jobling MA. Founders, drift and infidelity: the relationship between Y chromosome diversity and patrilineal surnames. Mol Biol Evol, 2009, volume 26, issue 5, pp1093–102
  8. Schacht LE, Gershowitz H. Frequency of extra-marital children as determined by blood groups. In: Gedda L (ed). Proceedings of the Second International Congress on Human Genetics Rome, Sept 6-12, 1961.
  9. G Mendel, 1963, pp 894-897.
  10. A study of 1748 Hawaiian families with 2,839 children reported a non-paternity rate of 2 to 3%.
  11. Ashton GC. Mismatches in genetic markers in a large family study. Am J Hum Genet. 1980, volume 32, pp601-613.

See also

External links

GNU head This article is licensed under the GNU Free Documentation Licence. It uses material from the Wikipedia article "Non-paternity event".