Ancestry, which also is in the business of DNA testing, allows users to send a vial of saliva to the company and receive in return a detailed genetic portfolio, including risk for some diseases and estimates of their ethnic ancestry.
The science is simple: Ancestry compares sections of your DNA with a "reference panel" of DNA samples that it knows correspond to a certain place (say, Italy or southern Africa) to try to identify a match. The new update expands the reference panel by a factor of five, so it should be more accurate.
An Ancestry spokesperson told the Detroit Free Press, "Almost all of our 10 million users saw a change – whether it is seeing a region broken out into more detail (e.g. specifying Sweden or Norway instead of Scandinavia), a small increase or decrease in a percentage from one of their regions or a more substantial evolution."