Kinney, McKinney & Variations
Lenhart & Variations
DNA Project notes

Non-Paternal Event (NPE)
This page was original titled False Paternal Event
15 December 2006

Non-paternal event, non-paternity event, false paternal event, false paternity, misattributed paternity: all these terms refer to a break in the Y chromosome line due to a formal or informal adoption, name change, "extramarital event" (infidelity), child known by other surname (mother's maiden name, stepfather's name), etc. There's no agreement about the rate at which these occur (the 5%-10% frequently reported as being used by geneticists may be based on folklore). Using a conservative estimate of 2%, in a group of 50 participants, we might expect that at least one would not match at all.

There is always a possibility that you could get disappointing test results. Samples that vary by three or more markers from the main group may do so for a number of reasons. One possibility is that they represent distinct lines either older or younger than the currently observed most frequent line. Another is that there has been a non-paternal event at an unknown time in the past. This means the male tested may be carrying the surname but his Y chromosome does not appear to be associated with that surname.

Types of non-paternal events include but are not limited to:

Pregnancy outside of a marriage
Pregnant female married man who was not father of child
Adoption (formal or informal)
Man married pregnant widow
Children known by step-father's name
Man took wife's name and/or children given the wife's surname
Man changed name - various reasons
Illegitimacy - child given mother's surname
Clerical error in recording administrative data such as assigning a name to the wrong person

It should be stressed that adoptions were quite common in every age: parents died by disease or war and a relative took in the children and raised them with their name, daughters had children out of wedlock and the grandparents (or other relatives) raised the children as their own. A teen-age girl who gets pregnant by one boy and marries another - for whatever reason - might be a more frequent occurrence than maternal infidelity in earlier generations. Taking into consideration the strong pressure against "unwed mothers" until the last generation or so, one might expect such cases to account for some of the paternal irregularity indicated by Y-chromosome testing. Very young mothers of first-child sons in the line could be indicators for a higher probability of this phenomenon.

A result indicating a non-paternal event would certainly be a disappointment to most participants. But your name is legally your name and a small sample size could be misleading. A DNA sequence suggesting a non-paternal event could be that of the original bloodline - e.g., 20 people are tested, 19 are very similar and yours is clearly different. It could be that the 19 descend from the same person 300 years ago who was adopted while your line links to the original blood line going back 800 years.


Faulty research can result in a non-match or a match to a different line than expected. For example, suppose a researcher traces an ancestor named John R. Kinney to an 1850 census in MO. The census indicates he was born about 1819 in MA. The researcher finds a publication about an MA Kinney line and looks up all the Johns in the index. He finds a John Robert Kinney, Jr., born in 1819, listed as a son of John Robert Kinney, Sr., who was born in MA. There is no additional information about JRK, Jr. The publication traces the family back to 1635 in England. The inexperienced researcher thinks this must be his John and links the line to the family in the publication. Later, a DNA test of the researcher does not match two other participants from the 1635 line. This could be due to a non-paternal event but it also could be due to faulty research. If the DNA project has many participants, our researcher may learn that he links to a different Kinney line (error was due to faulty research). If it is a large project and he has no matches, he will have to consider the possibility of a non-paternal event.



Some of the above was adapted (with permission) from the Blair surname project web site. The site also includes helpful DNA 101 and FAQ sections

See also:

Subject: Non-paternity rate [was Re: [DNA] Father-son Study by Univ of AZ] - December 07, 2004

The Abstract Factory
The above refers to "how many bastards are there, anyway?" at:

Who's Your Daddy?
Short report on: "Who's Your Daddy?" "Measuring Paternal Discrepancy and Its Public Health Consequences." Mark A. Bellis et al. in Journal of Epidemiology and Community Health, Vol. 59, No. 9, pages 749-754; September 2005.

December 19, 2005 World Science
Aug. 12, 2005 Courtesy BMJ Specialty Journals and World Science staff
<Around one in 25 dads could unknowingly be raising another manís child, new research suggests. The study is published in the September [year?] issue of the Journal of Epidemiology and Community Health.>

< . . . . "misattributed paternity." That's the phrase I employ from time to time now, as it covers both NPE and glitches in the paper trail. >
Ann Turner, November 13, 2006, post to ISOGG at, Subject:Re: [ISOGG] FW: Ysearch at the Conference.

Kinney, McKinney & Variations
Lenhart & Variations
DNA Project notes