DNA Origin Test: Where Do We Come From?

Every person, at some point in their life, asks themselves the eternal question: “Where do I come from?” These three words have haunted us individually, as a family, and even as a society, and have sparked our curiosity to the point of delving into our dreams. Did my ancestors fight in World War I? Does the blood of some revolutionary who was present at the storming of the Bastille run through my veins? Did my ancestors belong to the Eastern or Western Roman Empire? In which branch of Homo sapiens that populated the Earth is my lineage? We’ve always wanted to know where our origins lie in history and what we share with the civilizations that built the current cultures now spread across the five continents.

Currently, the answers to these questions may be found in a branch of evolutionary and population genetics studies known as genetic ancestry. Genetic ancestry applied to humans, or better known as DNA origin testing , studies the genetic relationships of one or more individuals with an ethnic group, a people, or a geographic location. These relationships generally study human genetic diversity, which would reflect the demographic/migratory movements of our species since its expansion nearly 100,000 years ago and compare it with that of current or past individuals or social groups. While it is true that our species has always sought to move across the planet, these migratory movements have not been as rapid compared to those that occurred as a result of globalization. Thus, ethnic groups and populations were more isolated and genetically homogeneous, a very important fact when developing references that will increase the precision of these studies.

Initially, DNA testing for population origins was conducted by studying differences in blood types among ancestral populations. For example, blood type O+ is more common in Latin America and Native Americans, while blood type B+ is more common in East Asia. These studies have evolved rapidly due to two factors: the emergence of new DNA sequencing technologies and the lowering of these costs. The compilation of DNA sequences in databases of different ethnicities and peoples, as well as the lower costs of genotyping and sequencing, led many companies to offer their customers the option of performing DNA tests for ancestral origins.

Currently, these commercial DNA tests allow for the estimation of the percentage of population admixture that left a mark on an individual based on mutation patterns . These mutations are compared with a reference data set generated from mutation frequencies calculated for both ethnic groups and different majority populations. There are several ways to calculate this genetic ancestry depending on the part of the genome being studied:

• Studying the pattern of mutations found on the Y chromosome can reveal which branch of the human genetic tree your paternal line is on. This is because the human Y chromosome is inherited directly from fathers to male offspring, maintaining it in a similar way to how a surname is maintained. In this way, you can trace a history from Adam of the Y chromosome, who is the oldest human with whom we all share certain mutations, to the last known branch of this tree and link this history to your paternal surname, even following the migration and differentiation routes of your ancestors.

• By studying the pattern of mutations found in the genes of your mitochondria , the cellular organelles that supply us with energy from oxygen and nutrients, we can determine the origins of your female ancestors. This is because the mitochondrial chromosome is inherited directly from mother to son. This allows us to explore the maternal lineage, from the Eve of the mitochondrial chromosome to the mutations that differentiate current populations.

• Finally, by studying the pattern of common mutations found in the remaining chromosomes as a whole, we can estimate the percentage of ancestry that cannot be captured in the previous cases. Thus, a higher number of mutations is used, taking into account the genetic relationships between your paternal and maternal ancestors. Due to the processes of genetic material exchange in these chromosomes, we can define different DNA blocks, which have different ancestral origins. In this way, these different blocks that make up an individual’s DNA are like the pages of a book that tells the story of their origins and can belong to various peoples or ethnic groups.

DNA origin test: What can we expect at the individual level?

These DNA tests are performed using the same tools used to study evolutionary relationships among humans in evolutionary genetics research centers.

Since 2007, when the first genetic tests began to be offered to consumers, the usefulness of genetic ancestry tests has grown in many ways, and they still have much potential to be discovered. The most relevant information this type of test can provide is knowledge of your roots beyond genealogy ; the estimated percentage of ethnicity can help trace the historical heritage of your surnames. Along these same lines, these tests are of even greater interest to adopted people and people with unknown origins, such as the famous Stolen Children, Holocaust survivors, or people of slave ancestry.

In addition to these uses, numerous unexpected uses have been found, such as uncovering infidelities, forensic uses, uses in health aspects due to diseases that are more common in some populations than others, discovering distant relatives, etc.

What should I not expect from a DNA test of origin or genetic ancestry?

• Similarities between different companies: Each company uses its own reference data, as well as its own algorithm, to calculate an estimate of belonging to one population or another. There is also variation between the genome positions of the platform each company uses in its analysis. This combination of variations causes the proportions for each ancestry to also vary.

• Bureaucracy: While it is true that in some countries a genetic test, usually a paternity test, can be used to grant citizenship, in the vast majority of countries a genetic ancestry test is not valid, nor is it common to use the results of an ancestry test as a way to enter a tribal group or apply for benefits for belonging to a minority ethnic group.

• Paternity: Although it can be helpful or even reveal secrets like infidelity, the DNA origin or ancestry test is not a highly reliable paternity test. If you need to take a paternity test or other kinship test, you can find information here .

What is the future of genetic ancestry?

In 2018, major genetic ancestry testing or DNA origin testing companies sold around 30 million tests. The growing interest and curiosity to learn more about our past, as well as technical improvements in sequencing and genotyping, are making tools and protocols increasingly refined, leading to increasingly accurate estimates. The most demanding ambition of this field is to bring this knowledge of ancestry to the health field, and therefore, numerous studies are associating ancestry with a predisposition to develop or avoid certain diseases . With patience, scientific method, and data, genetic ancestry will emerge as a new category in the world of genetic counseling.

Do you have any questions?