Power and Limitations of Inferring Genetic Ancestry

Abstract

Background: The recent emergence of technologies that capture and analyse genetic variation patterns obtained from a person's DNA sample has led to numerous academic and commercial endeavours to infer individuals' ancestries. In theory, a person's genome contains a wealth of readily accessible information regarding their ancestors, despite only some of our ancestors contributing to the DNA we carry. This makes genetic tests an attractive alternative to the painstaking reconstruction of family trees or directly contacting long-lost relations, particularly when, unless there are notable individuals in the tree, historical and genealogical records tend to diminish in frequency with each generation. However, while powerful, there are limits to what genetic data can unearth, as well as important assumptions underlying these analyses.

Methods: This review describes some of the early history and latest advances in techniques and data used to infer ancestry using genetics, highlighting both the power and limitations of current studies.

Conclusion: While genetics is a powerful means of exploring aspects of people's ancestry, a stronger focus on conveying uncertainty will allow both academics and non-academics to avoid the ever-present risks of over-interpretation.

FIGURE 1

Mitochondrial DNA (blue fill) and Y chromosomes (orange outline) are each inherited from a single ancestor matrilineally or patrilineally, respectively. They contain no genetic information from any other ancestors (grey figures with black outlines). The autosomes are represented by patterned rectangles, with one autosomal chromosome pair depicted per person. One chromosome in a pair is inherited from each parent, and the process of recombination affects the amount of DNA inherited from each ancestor at each generation. Relative to the mtDNA and NRY, the autosomal chromosome pair contains genetic material from many of an individual's ancestors, hence providing a more complete picture of their genetic history.