For DNA testing of close relatives, the purpose is generally related to legal or health questions and focuses on determing if a person is the child or grandchild of a certain other individual. The results of these DNA tests are specific and limited in their purpose. On the other hand, results from DNA testing for genealogical reasons serve multiple purposes and interpreting them can involve a complex process of analysis.
The Y-chromosome tells us a lot about a man, his ancestors, and his relatives. First, it tells whether two or more men share the same common male ancestor. Within this group, it shows whether men of the same surname are related through one ancestor and it also shows how many different ancestors a group of men share. Second, it shows which haplogroup a man belongs to. There are 28 haplogroups in the world.
Because of its nature, testing of mitochondrial DNA is used for learning about the distant origins of a person’s direct maternal line. It is used to determine mother to child relationships, but cannot reliably used to determine kinship in the relatively recent past.
Using Y-Chromosome Testing for Research
Using the Y-chromosome test, men can help answer long-standing genealogical questions or disprove long-standing genealogical myths. A common purpose for DNA research is to determine if there is a common link between two closely-related ancestors, even when a paper trail cannot be located. In the same way, if there is a large volume of records about multiple families sharing the same surname in the same area, a DNA test of the various male descendants can help sort out the families.
Although not common yet because of a relatively low level of interest on the European continent, people in the United States are connecting to those living in Europe and establishing their common ancestry. In some cases, this can help prove an historical immigration story.