Ancestry DNA kits are all the rage. But what can they actually tell us about our heritage? And should we rely on them at all?
We've all seen the ads; for under $100 and the minimal effort of spitting in a tube you can receive a report that defines your ethnic identity to minute percentages. Company's like 23and me, Ancestry.com and My Heritage offer to tell us 'where we really come from' and potentially link us with long lost distant relatives in faraway places or of a surprisingly different culture. But what does it actually mean and how does it work?
What is DNA?
DNA, or "Deoxyribonucleic Acid", is a complex molecule that contains all the information necessary to maintain a living organism. As a portion of DNA is passed down genetically to offspring, it also serves as a hereditary marker.
However, DNA is not predictable and it is not absolute proof of ancestry. While you do inherit your DNA from your parents, you may not inherit the same proportion of genes as your siblings or other relatives. So I may have a higher proportion of DNA from my paternal grandfather while my sibling could be more genetically related to a maternal great-grandmother. This explains why you may have a different hair or eye colour to other members of your immediate family. And why your DNA results may be inconsistent with another relative's or may not highlight an expected ethnicity.
How does Ancestry DNA testing work?
In an experiment using identical twins, several commercial ancestry DNA testing companies returned results that were different, not just between the companies but for each of the twins, despite them sharing virtually identical DNA. To understand how that is even possible, we have to consider how Ancestry DNA testing is performed.
An entire DNA sample is made up of about three billion parts, but companies that provide ancestry tests only look at around 700,000 of those to spot genetic differences. The DNA is then crunched by an algorithm and the results matched to a reference panel. As different companies use different algorithm's, different reference panels and often different reference regions the result can differ considerably.
In other words, the results are 'estimates' only based on differing data that is still evolving. Though there is science involved, it is not as accurate as medical DNA testing and therefore should be taken with a grain of salt.
"Finding the boundaries is itself kind of a frontiering science, so I would say that makes it kind of a science and an art," Dr Paul Maier population geneticist at FamilyTreeDNA
When asked why the twins' results from the same company differed it seems it may have come down to the algorithm potentially picking up on the minute difference in the twins DNA (about 1%) to produce different results.
The reference panels are also inherently problematic. Changes in regional borders, migration and limited datasets mean it's difficult to make assumptions of genetic differences that are significant enough to identify a person's origin.
Our ancestry DNA can only be assessed against those in the company's databank with similar DNA. The majority of people taking ancestry DNA tests and therefore contributing to the databank are of British, Irish or Northern European descent. As the databank grows, it's been possible to distinguish between origin countries within a region e.g. Norway or Denmark rather than the broader "Scandinavian". But it's taken longer to accumulate enough of a database to attribute to specific areas of Africa, Asia or South America. Additionally, ancestry DNA testing isn't available in all countries, and some, such as France and Germany, have banned their citizens from taking the tests.
The good news is, as the Database continues to grow, your DNA results could be different, but more accurate, in time.
Where are you really from?
In 2018, US Politician, Elizabeth Warren, was caught in a DNA controversy. Having previously claimed that she had Native American ancestry, US President Trump challenged her to 'prove it'. A DNA test confirmed that genetically she did have Native American genetic lineage and oral history of the family attributed that to a grandmother 6 or more generations previous.
Many in the Cherokee Nation, however, argued strongly that she couldn't claim to 'be' Native American as she hadn't the cultural and kinship ties that would recognise her as part of the community and a 'citizen' of the Cherokee Nation.
Similarly, those of us with "Viking" or "African" markers can't claim, on that alone, to be children of any particular nation. Even those millions of us who claim to be 'Irish' or 'Scottish' or 'English' based on an ancestor who emigrated as part of that nation's diaspora aren't generally considered citizens by the country's current government.
So what does our DNA tell us about who we are?
Our genetic history can be quite different from our cultural history. The results can surprise us and even challenge or change our idea towards race and identity. While our ancestral DNA is not a complete picture of who we are, it is evidence of our 'heritage', our family history. And finding out the secrets to our lineage continues to enthral us.
It's interesting to know where our ancestors came from, the conditions they lived in and the people they once called part of their family and community. It gives us a sense of who they were and the story of our past. It's particularly interesting for white Europeans who have found themselves in a part of the world where they don't have a genetic association to the native population.
One of the things people are realising as they get their DNA results back is how much we have in common. Many have located relatives around the world, although in some cases that has unearthed some difficult family secrets. It has also allowed us to see, from a broader perspective, our similarities with others, even where not directly related but who share similar DNA markers. We might never have considered we had African, Middle Eastern or Native ancestry and, no matter how small a percentage, its presence in us proves the people in our past once mixed with other cultures. We can see through our genes how they migrated and intermingled over the generations.
Knowing our identity is fundamental to our being. We want to know where we came from, who we "are". But our DNA lineage is only part of the answer. The rest we find in the present, the culture and connections we make and what we pass on.