In a short time, human genetic origins have become a billion-dollar industry. Until a couple of years ago, 26 million people worldwide had performed a so-called DNA analysis.
That is, they have sent some saliva or some cells from inside the cheek to a laboratory in the United States or Europe and then received a response with various percentages that – according to the advertisement – show the person’s “ethnic background”. For example: “Sweden and Denmark 55 percent, Norway 36 percent and Finland 9 percent.”
But what do these percentages stand for?
– These tests are good at finding which group or groups an individual is related to. Based on the example above, we can conclude that this individual is most closely related to people living in the Nordic countries today, but we can not say anything about the person’s origin. There are several reasons for this, says Mattias Jakobsson, professor of genetics at Uppsala University.
One reason, he says, is that DNA does not grow in the soil.
– The genome is with us humans and people are mobile and throughout history we have moved, between different places, countries and continents.
The percentages in the answer is a statistical comparison with a reference group. The answer thus reflects how genetically similar you are to the genome that exists in this group.
– The answer thus says nothing about where your ancestors come from, but how genetically similar you are to the people who live there today, which is a big difference because there have been several periods when we humans have been very mobile, says Mattias Jakobsson.
This is what it can look like on genealogy sites
Map: MyHeritage
Another problem is that the credibility of the answer is related to what the reference group looks like. In the larger companies, this group consists of genetic material from people recruited by the companies all over the world and, in some cases, from scientific studies. But if this “DNA collection” is incomplete, the result can be misleading.
– We say that you come from today’s population in Asia, but in the reference group there are no individuals from Asia but only people from Europe and the American indigenous population. Then the answer will be that you come half from Europe and the other half from the American indigenous population, because these are the groups you most resemble, says Mattias Jakobsson.
A third and perhaps even bigger problem is that the concept of “ethnicity” is vague. Of course, there is no “Swedish” DNA, or Scandinavian either, for that matter. The only thing that exists is a number of gene variants whose occurrence is different in different places on earth among those who live there today.
– There is nothing ethnic to read from DNA. Companies should be clearer about this, but they are not. Instead, these tests are marketed as showing where your ancestors come from, but that is more or less nonsense, says Anna Källén, associate professor of archeology at Stockholm University.
A popular theme in these contexts is the Viking. Because for some unfathomable reason, the internet seems to be flooded with people who want to find out if they have real Viking blood in their veins. Maybe not so much here in Sweden and Scandinavia, as in UK and the United States. Not only that. People are willing to draw very far-reaching conclusions if they think that is the case.
It shows it investigation as Anna Källén did together with the historian of ideas Daniel Strand. The study, published in 2021 in the New Genetics and Society, interviewed a number of people from the United States, Britain and Sweden who had all performed a genetic test that they believed showed a relationship with Vikings.
– It meant a lot to them and many, especially in the US, drew very far-reaching parallels between these “relationships” and characteristics of themselves or their families. For example, someone said that Viking genes could explain why so many men in their family had been aggressive. In the light of what DNA is and can tell us, such conclusions appear bizarre, says Anna Källén.
You share so much DNA with an ancestor from each generation
Provided that none of the ancestors are related to each other.
Graphics: Maria Westholm.
But above all, it was the Viking not any ethnic group. So there have never been any “Viking genes”.
– Instead, the Viking as we see it today is largely a construction from the end of the 19th century. So what these DNA tests do is that they confirm an image from the 19th century based on the idea that DNA can prove inherited properties from antiquity, which DNA can not, says Anna Källén.
One explanation for this is that the genome is “diluted” for each passing generation. Because if you have two parents, then you have four grandparents. Another generation back, the number of relatives who contributed to your DNA is eight. Ten generations back, the number is up to 1,000, and 20 generations ago it is over a million. 40 generations ago, around the Viking Age, the number of possible family ties will be several billion. That is, significantly more than the number of people that existed at this time. But even if many family ties go to the same individuals, which they do, the number will still be so large that you will be related to very many individuals. So, yes, you are probably related to Vikings, but you are related to a lot of other people as well.
But do these tests provide no information at all? Yes, because according to Mattias Jakobsson, they are really good at finding kinship.
– Ten years ago, these tests were almost no better than astrology, because the number of analyzed markers was so few. But now hundreds of thousands of markers are being analyzed and they are great at finding relationships, like third or fourth cousins. So there is really nothing wrong with the tests themselves, but the fault lies in the fact that people overinterpret the answer and read in things that do not exist, such as this with origin.
About 40 generations since the Viking Age *
For each generation, the genome is diluted by half, provided that neither parent is related to the other. Regardless, the number of people who have contributed to your DNA from the Viking Age onwards is extremely large.
* DN has calculated an average of 25 years between the generations.
Have you taken a similar test yourself?
– No, because I suspect it would be very uninteresting. I know that our family, dating from the 17th century, comes from southern Sweden. But if you have a more varied family history and are curious, I can definitely see a point with these tests, says Mattias Jakobsson.
Another aspect is integrity. Because what you do in practice is that you give away your genetic material to a private company, something Anna Källén believes that many consumers are probably not aware of.
– You give not only your, but also your children, DNA to someone else who you have given your permission to use it. Therefore, these tests are banned in France, for example. Because this DNA is taking the road somewhere and we do not know how it can be used in the future, she says.
Mattias Jakobsson is on the same thing:
– The most important thing is that you take an active stance and that you understand what you are doing when you make this information available to others.
Facts. Genome, genes and DNA
A genome is the total genome of a living organism. The genome consists of DNA, which is an abbreviation for deoxyribonucleic acid.
The DNA molecule is in the form of a double helix with two chains attached to each other. The human genome consists of about 3 billion such base pairs that are collected inside the cell nucleus in a number of macromolecules, chromosomes. In humans, all cells normally contain 46 chromosomes, or 23 chromosome pairs, except for the gametes, which contain only 23 chromosomes. In addition, there is also a small amount of DNA in the cells’ mitochondria that are inherited from the mother.
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