The popularity of DNA tests, which can now be purchased over the Internet for less than $100, has been increasing in leaps and bounds. The company AncestryDNA, for example, reported record sales between Black Friday and Cyber Monday 2016, and tripled those sales figures in the same period of 2017.1
Like many of the hundreds of thousands of people who are making these tests so popular, I have always been curious about my family tree.
I was born in the U.K. My mother's family, all from the English Midlands, were exceptionally tall and were all blue-eyed with light brown or red hair. My aunt believed that while we were pretty much English to the bone, the family name was Dutch, and that Dutch ancestry explained our height. My father's family, on the other hand, were dark, slightly built Londoners. My paternal grandparents died before I was born, but the family tradition was that they were Welsh. Our name, Thomas, was Welsh and my dad even told me the name of the exact village in south Wales that my great-grandfather came from. On the other hand, one of my uncles was convinced that the siblings' dark hair and eyes, and proudly large noses were evidence of Jewish ancestry.
Which is why I decided to jump on the DNA bandwagon.
What is DNA?
DNA is a long and complex molecule found in the cells of all living organisms. The basic building blocks of DNA are four chemical bases, adenine, guanine, cytosine, and thymine. These are joined together in pairs and strung in various combinations like the rungs of a ladder between two chemical strings which are twisted into a double helix.Credit: By Apers0n [Public domain or Public domain], via Wikimedia Commons
The DNA of each individual is unique. The sequence and combination of the chemical building blocks form a genetic code which provides instruction for the creation of new cells. As we grow, heal wounds or replace worn out cells in our bodies, our cells need to reproduce. They do this by splitting in two to create identical new copies of themselves which become part of the new cell2. This video explains the process:
The human DNA molecule while very thin, is an amazing three meters in length15. This long structure is packed into a fascinating structure called a chromosome so that it can fit into the miniscule nucleus of a cell.
Each chromosome in a cell nucleus is one half of an identical pair of chromosome twins. All cells within the human body contain 23 chromosome pairs except for eggs and sperm, which contain single chromosomes rather than pairs. When a sperm fertilizes an egg, the single chromosomes from the egg and the sperm each split into two. Each half of a chromosome in the sperm comes together with the split half of a matching chromosome in the egg to form a new pair. Thus the genetic information in the DNA of a fertilized egg provides a code for the cells of the growing foetus which gets half of its information from the mother and half from the father.3
The History of DNA Testing
The first person to identify genetic inheritance patterns was Gregor Mendel. In 1866 he published a paper based on his experiments with pea plants which demonstrated that peas passed on inherited traits such as pod color, size and shape according to predictable statistical patterns.
The second piece of the puzzle was the 1869 discovery by Friedrich Miescher of a complex substance in the nucleus of white blood cells which he named nuclein. This was DNA, which was finally identified as the key to controlling inheritance by Oswald Avrery in 1944. Subsequent investigation into the structure of DNA led to Marshall Nirenberg becoming the first researcher to sequence the DNA code in 1965. Based on Nirenberg's work, techniques were subsequently developed which gave researchers techniques for rapid DNA sequencing14.Credit: By West Midlands Police from West Midlands, United Kingdom - Day 253 - West Midlands Police - Forensic Science LabUploaded by tm, CC BY-SA 2.0, https://commons.wikimedia.org/w/index.php?curid=28731557
As DNA databases gradually became more comprehensive and laboratory techniques improved, the accuracy of DNA testing, as well as their popularity, improved dramatically.6
Uses of DNA Tests
Law enforcement agencies have been building DNA databases and using DNA testing since 1985. Forensic experts use genetics to determine whether or not material such as hair or bodily fluids found at a crime scene belongs to a suspect. The first U.S. conviction based on DNA evidence was of rapist Tommie Lee Andrews in 1987. Since then, DNA has been used in court to place many rapists and murderers at the scenes of their horrendous crimes. It has also been used to prove that wrongly convicted criminals are innocent, and to identify human remains.Credit: Tony Webster Own Work Public Domain via Wikimedia Commons
Non-human DNA tests are used in the field of wildlife forensics to tracking down criminal activity related to endangered species10. While researching this article I was also surprised to find several animal DNA testing service for various domesticated species including cats, dogs and horses as a service for breeders, veterinarians and pet owners12. One of these companies, Wisdompanel, promises dog and cat owners that they can understand their pet's personality traits by learning about their breed ancestry. Other potential benefits include screening for disease risks and inherited drug sensitivity11.Credit: By Rodney L Honeycutt - http://bmcbiol.biomedcentral.com/articles/10.1186/1741-7007-8-20 Unraveling the mysteries of dog evolution, CC BY 2.5, https://commons.wikimedia.org/w/index.php?curid=54652394
In the medical field, human gene therapy may be used to test couples for potential hereditary diseases, or to test a foetus for genetic conditions and birth defects. It may help in the search for cures for hereditary conditions, to match potential organ donors to organ recipients, or to track down blood relatives7. Genetic testing can also reveal inherited medical risk factors for diseases such as such as breast or colon cancer, and even a tendency towards weight gain13.
Anthropologists analyze DNA of ancient human remains to ascertain gender, to trace prehistoric human migration, or to identify familial relationships8. DNA research on ancient Egyptian mummies, for example, has revealed fascinating information about the genetic heritage of King Tut, while an extensive international study has cast light on European migration patterns and allowed researchers to “... follow over 4,000 years of prehistory, from the earliest farmers through the early Bronze Age to modern times.”9
But the most popular use of DNA is in the area of parentage and genetic geneology. It can be used to determine if a particular man is the father of a child. Adopted children may want to get information about their biological parents or to find out if they are at risk of protracting any inherited medical conditions. Even people like myself who are not adopted may be curious about their medical or cultural heritage, or want to track down long lost relatives4.
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Should I Worry about Getting a Test?
Before getting your genes tested, you should check out the reputation and reliability of various genetic testing services, and how the services they offer relate to your reason for taking the test.
The genetic testing service 23andMe offers to provide reports on the link between genetic traits and health16. However, you need to be aware that the results it provides are based on statistical probability rather than absolute certainty and that they may not always be reliable. Consequently, this company was recently taken to task by the Food and Drug Administration for selling what the FDA considers an unlicenced medical device of doubtful accuracy aimed at diagnosing disease17.
You should also research the company's policy on client confidentiality and data security. The genetic analyses offered by these services depend on stored genetic data. The larger the database the service has to draw on the more accurate information it can provide. So you need to consider whether you would be comfortable with your genetic information becoming part of a vast and growing database. You should also be aware that there are concerns that companies could potentially provide genetic information for research purposes or even sell genetic data to, for example, pharmaceutical or medical insurance companies17.
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How to Take a Test
When I decided to jump on the DNA bandwagon it was out of sheer curiosity. I had no privacy concerns. In fact I though it would be cool to contribute to potential future research by adding my small grain of information to this growing warehouse of knowledge.
DNA can be obtained from any cell in the human body, such as sample of hair, skin or saliva. While the police may use hair, skin or blood cells, commercial DNA tests use saliva.
I ordered my kit on line and when it arrived it came with detailed instructions on how to obtain and submit my sample. I simply took a cotton swab and rubbed it on the inside of my cheek and then placed the swab in a vial. I repeated the procedure with a second back-up swab, and mailed both vials in the padded envelope provided in the kit.Credit: By Aney - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=290822
When a sample arrives at the laboratory, the DNA is isolated from the cells on the swab. The patterns of various DNA chunks are then analyzed and compared to other samples in the company's database to find matches4 which could indicate a relative or a member of a related group.
Heritage DNA laboratories identify haplogroups, specific genetic patterns which certain groups of people have in common, and which indicate they may be descended from common ancestors5.
Results are generally available online in six to eight weeks. After a long and agonizing wait, I received an e-mail informing me that my results were ready. With a sense of growing excitement I signed up to the company's website and logged in to see what my test revealed.
I was aware that results can sometimes be surprising. Tests can sometimes unearth family secrets such as "unexpected paternity and secret adoptions,"18, babies (accidentally or deliberately?) switched at birth, hidden scandalous affairs or mysterious unknown relatives. They can also reveal unexpected ethnic heritage.Credit: By Source, Fair use, https://en.wikipedia.org/w/index.php?curid=32833899
In my case, I received not only confirmation of some things I already knew but also a few suprises.
Unsurprisingly, my DNA was approximately 70% English and 5% northwest European, presumably from the tall Dutch maternal ancestor who gave my mother her surname.
But I also found out that geographical residence and genetics are not necessarily related. There were no Celtic markers (Scottish, Irish, Welsh) to confirm my supposed Welsh heritage. The Jewish component was also surprisingly small, a mere 1.4% Ashkenazi Jew, but there was also a seemingly connected but unexpected 21% Eastern European. It turned out that one of my paternal grandparents was Eastern European and I had absolutely no idea.
In addition, there was a small but surprising remnant which came as a total surprise. If I had any connection to South Wales at all I had more in common with Shirley Bassey than famous Welsh poet Dylan Thomas because 2% of my DNA was Nigerian. Although this result was unexpected, I was not completely surprised. After all, Nigeria was a former British colony and many Nigerians have immigrated to the U.K. In addition, my father's city of London as well as Cardiff in my supposed ancestral South Wales have always been thriving international port cities.
A total and complete surprise, however, was that I am 0.9% Central American. It seems that I had a distant slave ancestor who was transported to Central America, perhaps the former British Honduras which is now Belize. Although I will never know the answer to this conundrum, my imagination has been running wild with visions of a mixed African and Central American ancestor who became a sailor or perhaps even a Caribbean pirate.Credit: By A. Park of London - imageThis media is available in the holdings of the National Archives and Records Administration, cataloged under the National Archives Identifier (NAID) 535745.This tag does not indicate the copyright status of the attached work. A
So if you do decide to get your DNA tested, keep an open mind and be prepared for a few surprises.
What do you want to learn?