Ancestry: How researchers use it and what they mean by it

Abstract

Background: Ancestry is often viewed as a more objective and less objectionable population descriptor than race or ethnicity. Perhaps reflecting this, usage of the term “ancestry” is rapidly growing in genetics research, with ancestry groups referenced in many situations. The appropriate usage of population descriptors in genetics research is an ongoing source of debate. Sound normative guidance should rest on an empirical understanding of current usage; in the case of ancestry, questions about how researchers use the concept, and what they mean by it, remain unanswered.Methods: Systematic literature analysis of 205 articles at least tangentially related to human health from diverse disciplines that use the concept of ancestry, and semi-structured interviews with 44 lead authors of some of those articles.Results: Ancestry is relied on to structure research questions and key methodological approaches. Yet researchers struggle to define it, and/or offer diverse definitions. For some ancestry is a genetic concept, but for many—including geneticists—ancestry is only tangentially related to genetics. For some interviewees, ancestry is explicitly equated to ethnicity; for others it is explicitly distanced from it. Ancestry is operationalized using multiple data types (including genetic variation and self-reported identities), though for a large fraction of articles (26%) it is impossible to tell which data types were used. Across the literature and interviews there is no consistent understanding of how ancestry relates to genetic concepts (including genetic ancestry and population structure), nor how these genetic concepts relate to each other. Beyond this conceptual confusion, practices related to summarizing patterns of genetic variation often rest on uninterrogated conventions. Continental labels are by far the most common type of label applied to ancestry groups. We observed many instances of slippage between reference to ancestry groups and racial groups.Conclusion: Ancestry is in practice a highly ambiguous concept, and far from an objective counterpart to race or ethnicity. It is not uniquely a “biological” construct, and it does not represent a “safe haven” for researchers seeking to avoid evoking race or ethnicity in their work. Distinguishing genetic ancestry from ancestry more broadly will be a necessary part of providing conceptual clarity.

The use of race terms in epigenetics research: considerations moving forward

“…First, by neglecting to distinguish between self-identified racial categories and assigned or assumed racial categories. Second, by the haphazard use and reporting of racial/ethnic variables in genetic research, that is, reliance on race without clearly articulating exactly what race represents ( Yudell et al, 2016 ; Dauda et al, 2023 ). These oversights risk not only perpetuating a misperception of race as genetically based, but, by misclassifying race, may also reduce the validity and reliability of the scientific research.…”

“…Analyses that include genomic sequencing to categorize individuals into ethnic or ancestral groupings are also faced with the limitations of discretizing a continuous and very complex variable ( Lewis et al, 2022 ). Ways in which ancestry data has been used in research shows that it is largely ambiguous and varies across studies, indicating that the field lacks consistent use and definitions of ancestry terms and interpretations ( Dauda et al, 2023 ). The field of epigenetics should continue to conduct empirical studies on the role of genetics in epigenomics.…”

Wrestling with Social and Behavioral Genomics: Risks, Potential Benefits, and Ethical Responsibility

“…Today, as we have said, the “populations” that result from this sample inclusion‐and‐exclusion practice are often called “genetic ancestries.” 61 As others have noted, 62 continental‐level genetic ancestry, especially, is imperfect as a proxy for genetic similarity. It is also problematic because these populations do not reliably map onto, yet they are easily and erroneously conflated with, social groupings such as race and ethnicity.…”

“…When using a genetic ancestry concept, it is important both to say that this is neither race nor ethnicity and to affirmatively specify what genetic similarity is and how it is being operationalized in the study. A recent investigation found that scientists use “genetic ancestry” in a variety of ways, including in ways they themselves cannot fully articulate or explain; while some of them view ancestry as closely related to genetics, others view it as only tangentially related 155 . For instance, researchers might explain that their high‐level goal (for scientific reasons they explain) was to include people in their study who were relatively genetically similar to one another and to exclude those who exceeded some threshold of dissimilarity, that one way of thinking about genetic similarity is the time since two people shared a common genetic ancestor, and that they operationalized that by using participants’ report that all four biological grandparents hailed from the same continent (or did not).…”

Commentary: Genomic, epigenomic, and transcriptomic signatures of prostate cancer between African American and European American patients

“…In addition, we believe that the use of the categories “African American” and “European American” mixes both self-identified race and the genetic ancestry construct of ‘European American.’ This introduces ambiguity and confusion in the population descriptors and could inappropriately imply categorical differences, when genetic differences are in fact gradual or clinal ( 4 ). In the discussion, the authors claim that it is “important to confirm and measure ethnicity information from samples using genetic ancestry informative marker data.” ( 1 ) The delineation between ancestry, genetic ancestry, and genetic similarity is complicated but important to state clearly ( 4 , 6 ). Neither “race” nor “ethnicity” can be confirmed or measured by so called ‘ancestry informative markers,’ ( 6 ) and the use of continental ancestry designations is not consistent with modern understanding of genetic variation in humans.…”