If I were genetic genealogy king for a day, I would replace
the term “Non-Paternity Event (NPE)” with a more comprehensive term –
specifically, “Exogenous Ancestry.”
Exogenous ancestry? That’s a mouthful, but what does it
mean? Well, it’s a term that I have
borrowed from biological studies to explain some of the discontinuity of single
source surnames with Y-DNA from outside of the family in question. I have been contemplating for some time of
using a different term from what is now commonly used in genetic genealogy –
non-paternity event (NPE).
Bryan Sykes and Catherine Irven (2000) first used non-paternity
event in the context of genetic genealogy to explain haplotypes that differed from
the typical Y-DNA signature of a surname.
It was a borrowed term as well, as it was used in anthropology and
sociology where the presumed father was not the father of a child. Generally, this referred to infidelity on the
part of the mother.
In genetic genealogy circles, the International Society of Genetic Genealogy’s Wiki cites least 13
different categories which have been considered as non-paternity events. While infidelity is one of these, there are
other scenarios where genetic genealogists have used this moniker to describe
the discontinuity between surnames and ancestry.
What's the Beef?
The term non-paternity event and its synonyms don’t neatly
fit every situation where it is used. It
assumes that the designated father (and even the child) is unaware of the child's ancestry. This is not always the case.
In some cases, there may not be a father in the picture and
the surname traveled from mother to child.
The birth father’s name was not associated with the child and there was
no “official” father from whom false paternity could be claimed. It wouldn’t be a surname discontinuity as it
continued from the mother; it would be a Y-DNA discontinuity.
In the case of complete adoptions, not only would the
paternity be different, but the maternity would be as well. Using a term such as “Exogenous Ancestry”
would better fit full adoption circumstances as not only is the paternal DNA different,
so is the maternal DNA. This term would
be applicable to discontinuities found in mitochondrial and autosomal DNA.
Name changes are often considered NPEs – however, these can be voluntary and NPE doesn’t fit the situation – I am not sure any term other than
“name change” would fit this scenario.
Finally, the term appears to pinpoint a given “event”;
however, we may not be able to identify a specific generation when this discontinuity
occurred. While a person’s recorded
ancestry may have confirmation going back several centuries, Y-DNA tells a
different story. Yes, there was some
sort of misattributed paternity, but where did this “event” occur in the
lineage? Can we find it – sometimes, but
not always. We know that somewhere along
the ancestral line exogenous DNA entered the picture.
Where did this Term, Exogenous Ancestry, Originate?
It isn’t an original term, although I have been sparingly using
“exogenous Y-DNA” since 2012 to soften the blow when reporting NPEs in my study.
While recently performing Google searches for terminology relating to DNA from outside
the family/clan/tribe, I found it used in the study of wolf and coyote
populations of North America.
Lupine biologists used it to describe DNA found in certain wolf
populations that originated from outside the pack – sometimes considered an
unusual occurrence. In addition, it was also
used when wolf DNA was present in populations of coyotes – especially in areas
where no known wolf populations existed – hence an ancestral occurrence (von
Holt, Kays, Pollinger, & Wayne, 2016).
Exogenous ancestry is broader term than non-paternity events, it is already used in mammalian DNA studies,
and it is a better fit to a variety of DNA discontinuities. Will it gain in
popularity? I hope, but sometimes
teaching an old dog, wolf, or coyote new tricks isn’t that easy. I would be interested in hearing your spin on
this term.
Sources
Non-Paternity Event (n.d.). International Society of Genetic Genealogy Wiki. Retrieved June 10,
2016 from http://isogg.org/wiki/Non-paternity_event
Sykes, B., & Irven, C. (2000). Surnames and the Y
chromosome. The American Journal of Human Genetics, 66(4), 1417-1419. doi:10.1086/302850
von Holt, B. M., Kays, R., Pollinger, J. P., & Wayne, R.
K. (2016). Admixture mapping identifies introgressed genomic regions in North
American canids. Molecular Ecology, 25(11),
2443-2453. doi:10.1111/mec.13667
