Are DNA tests rubbish?
Over the past 20 years, the number of genealogists who use DNA tests as one of their tools for research has increased substantially. For this test, the more people in the world who participate, the better the results become for everyone. Results are not perfect and there is much to learn about how DNA can better help individual researchers and increase our understanding of ethnic origin.
The increase in DNA testing stems from genealogists sharing their results and the hype of commercials that claim people can find their ancestors over the weekend or with one simple test. The weekend genealogist warrior conquering their family tree in 48 hours is far from accurate.
DNA tests for genealogy research is severally limited by the low number of human DNA samples on file. To be exceptionally accurate, we’d need DNA samples from all ethnic groups across the globe spanning the last 400 years, before people began to mass migrate.
DNA links us to our ancestors like no other body feature because we get an equal amount of chromosomes, which makes up our DNA, from each of our parents. In theory, our DNA provides a road map to our ancestors but in reality, there’s not enough known about it or enough samples throughout the world to create the map.
There’s been research completed that suggests we carry memories in our DNA, and that we are conditioned by those memories. Fear is one of our strongest emotions, and it is believed if our ancestors feared something — for example predatory animals — we may also have that fear.
In my mind, it is similar to instincts. Mothers instinctively know to care for their child, and fathers instinctively know to protect their families. Perhaps these instincts were passed through the generations through DNA.
There are three types of genetic ancestry testing used in genealogy.
The Y chromosome test tracks the Y chromosome that is only passed through the males of the family. Women don’t carry this chromosome, so only male members of the family can have this test done.
The mitochondrial DNA test provides data on the female lines of the family because the mother passes on her mitochondrial DNA. However, since both male and female receive it, sons and daughters can use this test to trace their mother’s line.
The third test is single nucleotide polymorphism.
It evaluates a large number of variations across a person’s entire genome, tracing the lines of both parents. You’ll often see researchers post these results, stating they are 25 per cent of this and 35 per cent of that ethnic group.
In a BBC Radio 4 in Four interview (http://www.bbc.co.uk/ programmes/p05z4m57) with genealogist Debbie Kennett, the interviewer asked if DNA results were rubbish?
Kennett explains DNA results are a tool, but they can’t replace actual research because DNA looks at the differences in populations one thousand years ago or more, not individual family lines. They can pinpoint a continent, but narrowing DNA to a particular country is tough.
With regard to receiving different results when having tests done by different companies, she said each company collects different population references, and they use different algorithms.
For example, if a company has completed 100,000 DNA tests and the majority of those who provided DNA were from Ireland, United Kingdom and Europe, then there are no DNA references from every other place on the planet.