There is a certain occurrence in genetic genealogy called a Non-Paternal or Non Paternity Event. This is a break in the ancestry of a person’s Y chromosome and surname. A person named “Smith,” for instance, might have a Y chromosome that is clearly “Johnson.”
A non paternal event can occur when an adopted male takes the surname of his adoptive family, or a male child takes his step-father’s surname, or a male child takes his mother’s surname (undoubtedly there are other circumstances as well).
When a break in the Y chromosome is suspected or confirmed, it is possible that the break might have occurred 1,000 years ago, 100 years ago, or with the testee’s birth.
An article in The Atlantic titled “Who’s Your Daddy” addresses the ‘unintended consequences of genetic screening for disease.’ Or, in some cases, the unintended consequences of testing for genetic genealogy. The author, Steve Olson, recently underwent genetic genealogy testing:
“A scientific officer at a genetic testing company knew that I was interested in genealogy, and he had offered to run my DNA through a sequencer. A few weeks earlier, I’d swished mouthwash inside my cheeks, sealed the mouthwash in a tube, and mailed the tube to the company.”
The results of Mr. Olson’s (when I say that name out loud, all I can think of is ‘Little House on the Prairie’!) test revealed that his DNA was what he predicted it would be – of Scandinavian descent.
However, as Mr. Olson points out, this doesn’t always happen. The article cites Bennett Greenspan, of Family Tree DNA, as stating that “any project that has more than 20 or 30 people in it is likely to have an oops in it.” This aligns well with the traditional belief that anywhere from 5 to 15% of men are not the actual biological fathers of their children. Following this out 10 generations, there is a 40% chance of a non-paternal event!
Along the same lines, a recent article was published on the Wall Street Journals ‘informedreader’ blog titled “As DNA Tests Spread, So Do Nasty Paternity Surprises.” The article cited Steve Olson’s piece in The Atlantic.
I must admit, I have a deep understanding of this issue and the effect it can have on tested individuals. I have a solid paper trail to
My first thought was a non-paternal event. I even asked my Mom whether my dad was actually my dad (I was 99.9% joking, of course)! I was so proud of my German heritage, and here I was faced with the possibility that I wasn’t German at all.
However, after a few months, new results showed that other people belonging to the unique subclade of R1b1c also originated in the same area of
Thanks to Hsien at EyeonDNA for her help!


2 Comments
Thank you for making a complex subject easy to understand. I am enjoying the articles very much, and I’ve added a link on my own blog to this one.
Janice
Hello Blaine,
Thank you for visiting my personal blog. Have you been to my genealogy blog yet ?
http://carrollfamilysaga.blogspot.com/
I think that you have some fascinating topics in your blog.I have read articles on DNA testing, but I have not yet took the plunge.
You have a nice day and keep up the great work.
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[…] Note: Blaine writes more about unexpected results in his post - Genetic Genealogy and Non-Paternal Events. […]
[…] Mr. Neill posted a follow-up to his DNA post. In his post, Mr. Neill describes one example where a non-paternal event results in two related lines appearing as though they are unrelated. Non-paternal events are a big […]
[…] that they are not related after all. Testing can reveal secrets about family relationships, such as nonpaternity events, that would have never been known before. Fathers, mothers and children, or sisters and brothers […]
[…] you understand the risks associated with genetic genealogy (such as the detection of non-paternal events and other risks) and are ready and willing to embrace the results to learn more about your genetic […]