DNATesting.com says that DNA tests take up to two business days, starting from the day the lab first receives the samples. The testing process for both legal and personal interests is the same.
However, the collection process of a legal DNA test is different than that of a personal interest DNA test. This is because the collection of the DNA samples are handled by a third party during a legal DNA test. Regardless if its a legal or personal interest DNA test, the results of the test can be delivered via email or standard mail. Receiving results via email speeds up the process.