DNA testing for Genealogy

Modern DNA testing can now be used to corroborate or expand your family tree. A number of UK and US based companies now offer Y-chromosome tests that can prove whether people are closely related or not and even give a strong indication of how recently their common ancestor lived. In addition, well over a thousand projects have now been set up which study particular UK/Ireland surnames using the tests, or particular regions of the islands (eg Scottish Borders). It is not necessary to have a 'regional' surname, as even occupational surnames such as Smith can benefit from DNA testing to help sort out whether names are closely related or not.

How it works

A male participant is sent a kit containing a small brush. This is used to take a swab sample from inside the cheek. It is then stored in preservative and sent back to the company for lab analysis. Your result will consist of a series of numbers - these are repeat counts from sections of your DNA called Short Tandem Repeats. The particular combination of counts is known as your haplotype. Over time these counts will change through a 'mutation' event during transmission from a father to a son - one marker might change from a repeat count of 14 to 15, say. It is these mutations that cause the DNA test results to diverge and help us trace the family tree - or distinguish who is in the tree from who is not. Your close male relatives will have the same or near identical haplotype and unrelated people will typically have quite different ones. Some illegitimate births may be unveiled as such although of course they might be due to a close relative in which case they may not be distinguished by the test.
The names and order of presentation of these repeat counts are arbitrary. Having said that, some are already known to be faster at mutating than others so it is always worth looking at which markers two profiles differ on.