DNA testing

DNA testing is simple. The laboratory sends you a little brush, like a tooth brush, which you rub on the inside of your cheek and send back to them. The results are treated with the strictest confidence, but you can share the genealogically-useful aspects of the results with others if you wish, and doing so will help you understand a huge amount about your origins.

Although the science of genetics is intensely complicated, the application of DNA testing to the study of our origins is simple. DNA tests can provide estimates of your ethnicity (see ‘FamilyFinder’, below) and they can also tell you about the ‘deep ancestry‘ of certain genealogical lines.

The two genes that are relevant for ‘deep ancestry’ here are the Y chromosome, which passes down from father to son, down from our earliest male ancestor, and the mitochondrial (mt) DNA inside the mother’s egg, which passes down from mothers to all their children, but which is only passed on by daughters to their offspring. This mitochondrial DNA goes back from our mothers to their mothers and so on back up the female line to our earliest female ancestor. Mutations in both lines result in identifiable haplogroups and sub-haplogroups, which together form two branching family trees of humanity, one following the male line and the other following the female line.

Of the two, mitochondrial DNA mutates much less often, but the Y chromosome mutates very frequently and results in a much more detailed tree, whose many sub-sub-sub-(etc)branches are still being identified.

We can all have a test on our mitochondrial DNA, but only men can have Y chromosome tests (because only men have Y chromosomes). Women are not excluded: you can have your father’s Y chromosome tested, or if he is not alive you can have a test on your brothers’, or your father’s brothers’, or their sons’, or your father’s father’s brothers’ sons’ Y chromosomes – anyone in your family who shares the same male-line ancestry as your father will do.

The up-to-date details of the human pedigree, as defined by female-line mitochondrial DNA, is at www.phylotree.org/tree/index.htm. A detailed pedigree of humanity as defined by the male-line Y chromosome is on the website of the International Society of Genetic Genealogy: www.isogg.org/tree/. Both trees are constantly being modified and tweaked as new genetic evidence comes to light.  I have created a simplified version of the Y chromosome tree, focused on my own haplogroup, G. One focused on haplogroup R, which is the commonest in the British Isles, is in my book In Search of Our Ancient Ancestors, which also includes simplified trees of both the male and female line pedigrees of the human race, as defined by genetic testing.

You can also watch a short  interview with me about the potential of genetics to tell us more about our ancient origins, which was filmed at the Who Do You Think You Are? Show in Olympia a few years ago.

Since 1999 I have worked closely with Family Tree DNA, which pioneered making DNA tests available at affordable prices, and which, over the years, has honed and developed the range of tests available. They have a substantial database, which is essential for making valid comparisons with others who have been tested, and they have an excellent reputation in the field. Because I sung their praises so highly in my book  In Search of Our Ancient Ancestors, they have made me an  Affiliate, and can track any orders made and pay me a (very small!) commission.  Another advantage of your using  Family Tree DNA is that I understand how their system works and can help you make sense of the results when they come.

On Family Tree DNA‘s main page you will see a rather confusing array of products available, but if you go to the bottom of the page and click on the blue hyperlink to ‘Products’ you will be directed to a page where the three types of test are listed much more clearly:

Y DNA. This looks at men’s Y chromosomes, as explained above. You can chose (by scrolling down the page) to have 37,  67 or 111 markers tested. You will get good results from 37 markers, but even greater precision from the 67 and 111 markers. By comparison of your results with their database they will be able to predict your genetic haplogroup and your sub-group within it, and this will come as part of your results. (Later, to hone your knowledge of your sub-sub-sub (etc) group, you may have the option of paying a small amount for extra tests, as they are developed, which are specific to sub-sub-sub(etc) groups to which you are likely to belong).

As you will see from the ‘projects’ link at the bottom of the Y DNA page,  Family Tree DNA runs a great many projects for specific surnames, and for specific genetic haplogroups. By joining one and contributing your results, you will learn more about your origins and you will add to the sum total of knowledge about the surname and sub-haplogroup concerned.

MtDNA. This looks at everyone’s mitochondrial DNA, as explained above.

FamilyFinder. This is a different sort of test altogether, which looks at your autosomal DNA and compares the results with other people in FamilyTreeDNA’s enormous database so as to identify cousins and enable ethnicity testing. It provides an estimate of your likely ethnicity, broken down into percentages. These can only be estimates, but they can be interesting and sometimes surprising. Say, 87.5% of your genome matches people who say they are of Irish origin; in that case the test will tell you that seven eighths of your ancestors probably came from Ireland. If 12.5% matches people of, say, Eskimo origin, the test will say that one eighth of your ancestry was probably Eskimo. That may be the first time you realised you had an Eskimo great grandparent!  Equally, if you suspect you have, say, a quarter French ancestry, such a test could quickly confirm or deny this. The FamilyFinder test will also tell you how closely you are related to any of the other people who have already been tested. The results will tell you if you are a close cousin of someone else, but it can’t tell you how –  it may be through your father or mother, or either of their parents (etc), and it can sometimes be quite a puzzle to do the genealogy and work out what the connection was. However, this test is immensely useful if you want to know if you are related to a specific person (maybe you think your grandmother was the illegitimate child of someone else’s great uncle, for instance): you and the other person simply take one of these tests each. When your results come back you will see if you show up as close relatives of each other or not. If you do, you will know that your theory was correct.

AA BOOk coverFor more about the way your genetic results links you into the greater story of humanity and of life on Earth, see my book In Search of Our Ancient Ancestors.

I have created an example of how to link your family tree to your genetic results.

You can have your family tree traced back  using records, to find out as much as possible about your individual ancestors up the male and female lines.