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  • Writer's pictureMyrna Driedger

DNA & genealogy – discovering your background

What would you think if you discovered that your ethnicity was vastly different from your sibling’s though you have the same parents? I know what I would have thought! Well, genealogy and DNA testing can provide some interesting and often unexpected results. For example, one man was surprised to find out that his ancestry showed that he was 70 per cent British and 30 per cent Irish and his sister was almost the complete opposite. How could this be?

The first human genome project started in 1990 and was completed in 2003. It cost $3 billion to complete the DNA study on one person and involved 20 different universities around the world. It was the largest international biological research project ever done. Since that time, DNA testing has become much more common.

There are several types of DNA testing, and they all have different uses. For example, if you are interested in DNA testing for medical purposes – to discover if you have a breast cancer gene, for example – that is a different type of DNA test than one testing for ancestry. Scientists are even able to do testing in order to create tailor-made cancer treatments. The down side of the results of this type of testing is that some insurance companies are refusing life insurance coverage for people with certain genes.

If you are interested in finding out about your ancestry, you are generally seeking to determine your ethnicity as well as find other relatives. This is a different type of DNA testing, one that does not reveal any medical information. So there is no danger of being refused life insurance. Three basic tests are used for this purpose:

  • Y-chromosome (Y-DNA) tests for the direct paternal line,

  • mitochondrial DNA (mtDNA) tests for the direct maternal line,

  • and autosomal DNA (atDNA) tests for finding matches on all your ancestral lines.

Males inherit a y-chromosome from their father, through his father, his father, his father, etc., on the direct paternal line. This chromosomal DNA testing can give you information going back 5,000 years. Everyone inherits mitochondrial DNA from their mother, through her mother, her mother, her mother, etc. on the direct maternal line. Autosomal DNA is inherited from all ancestral lines, so anyone can be tested and your matches may descend from anyone on your pedigree chart, up to about six generations back.

So how is it possible that a sibling can have completely different ancestry results even though you have the same parents? We get 50 per cent of our DNA from each parent. So that means we only inherit up to 25 per cent of our DNA from each grandparent and 12.5 per cent from each great grandparent. But what we inherit from our grandparents and great grandparents is totally random. So, if we have one grandparent who was 100 per cent British, we could inherit as little as one per cent of the British ancestry while our sibling could inherit 25 per cent. The same would be true of all four of our grandparents. As we go through each generation we lose a lot of our “background”, which explains why one sibling could be 70 per cent British / 30 per cent Irish while the other sibling could be 10 per cent British / 90 per cent Irish.

Several companies do this type of DNA testing and, if you are interested, one way of deciding which company to go with is to find out the size of their database. Because your DNA results are added to the database to find your ancestors and current relatives, it only makes sense that a company with the largest database would be able to give you the most complete results. One of the most common ones that we see advertised is and it currently has the largest database. But the cost of DNA testing has come down considerably since the original one at $3 billion!

Once you have received all your results you can upload them to a database called GEDMatch at GEDMatch is a free service that helps you find even more relatives who have also completed DNA testing and chosen to upload their results. So not only will you find more matches, the matches you find will be more likely to have an interest in genealogy. It will help you to interpret your genome.

In addition to pursuing DNA testing, you can also contact the Manitoba Genealogical Society, which can be found online at or by phone at 204-783-9139. The Manitoba Genealogical Society has many resources to help you trace your family background, such as a large collection of books on genealogical research, local and family histories, with an emphasis on Manitoba, maps and periodicals from other societies in Canada and other countries. An individual membership currently costs $50 and entitles you to use all their resources in your search.

If you decide to embark on this journey, I wish you luck and good “sleuthing”!


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