By: LaKisha David and Leia Jones
Between 1501 and 1866, 10.5 million enslaved Africans were taken from families and communities and disembarked in various diasporic locations in the world as part of the Transatlantic Slave Trade (Slave Voyages v2.2.3, 2019). With very few exceptions, genetic genealogy is the only way for people of African descent in diasporic locations to identify their extra-extended relatives among the descendants of those who remained in Africa. African Americans are increasingly engaging in historically significant processes of reunification with African relatives by using genetic genealogy to identify members of their ancestral families. By inference, families that were separated during the Transatlantic Slave Trade are reuniting. Researchers studying family formation or family reunification need to be cognizant of the methods of using genetic genealogy to identify biological extra-extended relatives.
In this methodological blog series, we demonstrate the use of publicly accessible genetic genealogy methods to identity genetic extra-extended relatives. There is an archive within the human genome which can provide information about an aspect of family history such as maternal or paternal ethnic lineages and biogeographical ancestry (BGA) estimates (Wagner, Cooper, Sterling, & Royal, 2012). One of our objectives was to identify genetic relatives among populations that experienced significant historical mass trauma, specifically family disruptions by the Transatlantic Slave Trade, by using criteria from established findings within population genetics that provides strong evidence of relatedness between our Ghanaian project participants and diaspora African Americans within the GEDmatch database. Specifically, we identified Ghanaian and African American dyads who shared a common ancestor within 10 generations (i.e., sharing ancestral great grandparents) in contrast to studying genetic matching within a biologically determined African ethnic group which has been the focus of previous genetic genealogy studies involving Africans and African Americans.
The aim of this methodological blog series is to inform family and identity researchers about the use of genetic genealogy as a method of inquiry and intervention in identifying close and extra-extended relatives. This series is based on our study that explored family identity among Ghanaians who interacted with their diaspora African American relatives we discovered using autosomal genetic genealogy. In this series, we provide our rationale for selecting publicly available autosomal genetic genealogy services for genetic matching and the specific criteria drawn from population genetics to identify genetic matches. We present the results of our genetic matching and discuss our finding diaspora African American relatives of our participants from Ghana and the inference that families that were separated during the Transatlantic Slave Trade are reuniting. We then provide details of our materials and methods, including our rationale for selecting our participants and steps researchers unfamiliar with population genetics could duplicate in their research involving a reunification or biological relatedness element. We conclude with ethical considerations in the use of genetic genealogy as a tool in international research.
Part 2: Genetic Genealogy Information Type for Genetic Matching
Part 3: Criteria of Relatedness for this Study, Results, and Discussion
Part 4: Materials and Methods
Part 5: Conclusion and Reflections and Thoughts
Wagner, J. K., Cooper, J. D., Sterling, R., & Royal, C. D. (2012). Tilting at windmills no longer: A data-driven discussion of DTC DNA ancestry tests. Genetics in Medicine, 14(6), 586.