Today, computer technology and the beautiful people who volunteer their time to transcribe documents into an accessible database have created giant shortcuts in time and effort. The paper trail will never disappear from importance, as it is a major source in authenticating and documenting. If any disputes arrive over the history of a family, it will most likely be the offering of an original document which will end the debate. DNA arrives on the scene as an independent resource which can substantiate other researching techniques.
It cannot be over-stressed that DNA should not be used until a researcher is sure that all other resources of documentation has been exhausted. It makes no sense to prove with DNA testing what could be discovered by finding a birth certificate.
There are three main reasons to use DNA testing in the field of genealogy, as follows:
1) To resolve the issue of whether a specific individual is linked genetically to another individual or to your family tree.
Sometimes circumstantial evidence may point to a connection with another who is listed in the same geographical area, or even the insistence by doubtful sources that a particular individual was part of a family line. By testing a male in your family line and a male in the disputed branch of the tree, DNA can quickly prove or disprove such a link. This could also prove or disprove whether an individual had been adopted or born into the family.
2) To resolve the confusion surrounding individuals or families with the same or similarly spelled surnames.
A collection of researchers who were members of the Owen Association were faced with this dilemma. Because a large portion of the records in a Virginia county were destroyed in the war of 1812, many researchers found themselves linked to some one of eight families huddled with in a few miles of each other. Through DNA testing, six of the eight families were discovered as not being related to each other. This also provided a baseline for future members to use. As new members tested their tree, they discovered which one of the main 19 separate DNA groups of Owens they were related to.
This can also help with the plethora of surname spelling variations which can also cause hardship not only in verifying certain branches, but in verifying, perhaps, the actual surname that would lead a family line to the homeland prior to America.
3) To find out one's original ethnic origin or ancestry.
This last reason has very little actual application to the general family historian. Genetic origin or Haplogroups rely on mutations of the genetic sequence to discover original ethnic origin or ancestry. Haplogroups refer to the original branches of the human tree. Each of these groups are normally associated with a geographical region. This portion of the science relies on natural mutation rate which is between 333 to 500 years. In genealogy this may mean that for every 15 to 25 generations one mutation occurs.
However, discovering that your line was of a common group in a European population and that group was first believed to have arrived some 10-12,000 years ago when the ice sheet melted, doesn't really help out the historian who hasn't found a ship's manifest that showed when one's ancestor came across the Atlantic.
DNA is a science based on accuracy. It is, of course, accurate only as long as the test is done correctly and as long as the source of the sample is taken without jeopardizing its make up. Having said that, DNA is a tool, and in much of the same way as repairing a car, it is the chorus of several tools together which increases the efficiency in the results.
A researcher will find it beneficial to coordinate the DNA testing with others and, if possible, as part of a surname group which all use the same lab. In this way, not only does one get a larger sampling to compare with, but all of the samples will be processed by the same method. The use of different labs may result in the use of different labeling techniques, which would make it difficult to reconcile if gene 12 is labeled gene 13 in a different lab.
Now that you know how DNA can help, the next question, is it a step you want to take? Happy hunting.