Thinking of DNA testing, wiki is where a great number of people are finding some of the answers they are looking for. This on-line encyclopedia is a valuable free source of information available to the world.
This particular topic has a very good and in-depth article. Right in the beginning, it becomes clear that with genealogy DNA testing a person or family can trace their family roots back through the generations.
For those looking for information on genetic diseases or genetic disorders, there is little to no information that could be helpful. There is some known information that might be discovered when an analysis is done to a DNA sample, like when a specific marker is missing.
There are also commonalities of specific haplogroups for long life and other characteristics. But this is not the purpose or scope of this type of testing. Its main purpose is for genealogical research of a family.
The number of markers that are tested determines the accuracy of the testing. There is a 12 marker testing, 37 marker testing, and a 67 marker testing. With an increase in markers, there is a more accurate confirmation of the testing results. An example is if a 12 marker test was conducted on a sample. A test that matches back 7 generations would have a 50% likelihood of a match. With 67 markers tested, the results would be at 95% accurate.
With the ease at which the sample can be taken, from the inside of the cheek, and the relatively low cost which can be below $500, the popularity of this type of analysis is on the rise. This has lead to a rise in DNA testing. Wiki is a great source of general information.
Do be aware that the information shown on a Wiki is provided by volunteers and it may change at any time. Do your homework. For more even details, a dedicated site on this topic like this one is preferred by many.