Genetic genealogy

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Genealogical DNA testing first became available on a commercial basis in the year 2000 with the launch of Family Tree DNA and Oxford Ancestors. Since then other companies have been established, dozens of relevant academic papers have been published, and thousands of private test results organised by surname study groups have been made available on the internet. The comparison of results may be complicated by the fact that some laboratories use different markers and report the results in different ways. By 2007 annual sales of genetic genealogy tests for all companies, including the laboratories that support them, were estimated to be in the region of US $60 million.^[2] By January 2013 it was estimated that around two and a half million people around the world had paid for a consumer genomics test, with the majority of participants testing for genealogical purposes.^[3]

Genetic genealogy is also concerned with phylogenetic analysis. The phylogenetic tree of Y-chromosomal haplogroups, popularly known as the Y-DNA haplogroup tree, is maintained by a volunteer team of researchers from the International Society of Genetic Genealogy. The phylogenetic tree of global human mitochondrial DNA variation, known as the mtDNA tree, is maintained by Mannis Van Oven and is published on the Phylotree website. Knowledge of one's placement on the Y-DNA or mtDNA tree can extend the genealogy of the patrilineal or matrilineal line beyond the traditional paper trail, and it is sometimes possible to make inferences about the geographical origin of the patrilineal or matrilineal line ancestor.

History

See Timeline page: Timeline:History of genetic genealogy

The earliest use of the term genetic genealogy found to date was on 20 February 1989 in an article by Tom Siegfried in the Dallas Morning News entitled "Genetic genealogy and the search for 'Eve":

"In searching for the roots of the human race, scientists have traditionally relied on the fossil records found in ancient rocks. Of course, scientists have long known that we all carry a record of our roots in our genes. It's just that the record in the rocks has been easier to read. Lately, though, practitioners of genetic genealogy have found methods to search for the woman from whom we all are descended. She is popularly known as Eve."^[4]

The next recorded reference was in June 1996 when Helene Cincebeaux gave a presentation on the subject of "Genetic Genealogy" at the Federation of East European Family History Societies' conference in June 1996 in Minneapolis.^[5]

The first published reference to the use of the term in the context of a surname DNA project was on 9 November 1998 with the publication of an online article entitled "An introduction to genetic genealogy" by the genealogist Alan Savin, who launched the first surname project by a genealogy hobbyist in 1997.^[6]^[7]^[8]^[9]

Y-chromosome DNA tests

See main article: Y chromosome DNA tests

Y-DNA testing involves short tandem repeat (STR) and, sometimes, single-nucleotide polymorphism (SNP) testing of the Y-chromosome. The Y-chromosome is present only in males and reveals information on the patrilineal line. These tests can provide insight into the recent (via STRs) and ancient (via SNPs) genetic ancestry. A Y-chromosome STR test will reveal a haplotype, which should be similar among all male descendants of a male ancestor. SNP tests are used to assign people to a patrilineal haplogroup, which defines a much larger genetic population. A Y-DNA test is typically used in surname research and results are collated within surname DNA projects.

Mitochondrial DNA testing

See main article: Mitochondrial DNA tests

mtDNA testing involves sequencing or testing the HVR-1 region, HVR-2 region or both. An mtDNA test may also include the additional SNPs needed to assign people to a matrilineal haplogroup. Family Tree DNA offers a full mitochondrial sequence (FMS) test which sequences the entire mitochondrial genome.

Autosomal DNA testing

See main article: Autosomal DNA

Biogeographical and ethnic origins

See main article: Admixture analyses

Additional DNA tests exist for determining biogeographical and ethnic origin, but these tests have less relevance for traditional genealogy.

Videos

The three main types of DNA test (Y-DNA, mtDNA and autosomal DNA) are explained in this video presentation entitled DNA - Brick Wall Buster? by Maurice Gleeson which was the subject of the Irish Genealogical Research Society's Spring Lecture presented at the National Library of Ireland in Dublin on 19th March 2013.

In October 2007 genetic genealogy testing was featured on the US TV programme 60 Minutes hosted by Lesley Stahl. See Rebuilding the family tree: Lesley Stahl reports on the hopes and limitations of genetic genealogy.

Benefits

Genetic genealogy gives genealogists a means to check or supplement their genealogy results with information obtained via DNA testing. A positive test match with another individual may:

verify existing research
establish that two surname variants are related
provide locations for further genealogical research
help determine the ancestral homeland
discover living relatives
confirm or deny suspected connections between families
prove or disprove theories regarding ancestry

Drawbacks

People who resist testing may cite one of the following concerns:

Cost
Quality of testing
Concerns over privacy issues
Loss of ethnic identity

Finally, Y-DNA and mtDNA tests each only trace a single lineage (one's father's father's father's etc. lineage or one's mother's mother's mother's etc. lineage). At ten generations back, an individual has up to 1024 unique ancestors (fewer if ancestor cousins interbred) and a Y-DNA or mtDNA test is only studying one of those ancestors, as well as their descendants and siblings (same sexed siblings for Y-DNA or all siblings for mtDNA). However, most genealogists maintain contact with many cousins (1st, 2nd, 3rd, etc., with different surnames) whose Y-DNA and mtDNA are different, and thus can be encouraged to be tested to find additional ancestral DNA lineages.

Scientific and academic papers

Calafell F and Larmuseau MHD (2016). The Y chromosome as the most popular marker in genetic genealogy benefits interdisciplinary research. Human Genetics. Published online 5 November 2016.
Khan R and Mittelman D (2013). Rumors of the death of consumer genomics are greatly exaggerated. Genome Biology 2013; 14:139. Published 26 November 2013.
Larmuseau MHD, Van Geystelen A, Van Oven M and Decorte R (2013). Genetic genealogy comes of age: perspectives on the use of deep-rooted pedigrees in human population genetics. American Journal of Physical Anthropology 150 (4): 505-511.
King TE and Jobling MA (2009). What’s in a name? Y chromosomes, surnames and the genetic genealogy revolution. Trends in Genetics 25; 351-360.
Johnston J and Thomas M (2003). The science of genealogy by genetics. Developing World Bioethics 3(2):103-108.
Nash M (2006). Genetic tests for genealogy: 10 reasons to be wary. L’Observatoire de la génétique issue no 29, septembre-octobre 2006. Also available on the author's website here.
Brown K. Tangled roots? Genetics meets genealogy ($). Science 2002: 295 (5560): 1634-1635.