The results of your test are not private from authorities or anyone with a warrant. If my brother commits a crime and leaves DNA evidence, I am now a prime suspect.
If we somehow use DNA as an authentication source in the future, you don’t want your’s compromised due to lack of security. Biometrics are not a security factor that you can revoke. Once it’s revealed there is no going back. Rediculous? Just a few years ago fingerprint scanners were part of science fiction movies and today they are standard on all but low end cell phones.
Eventually someone is going to figure out how to do DNA non-invasively and cheaply. when they do expect it to become a source of Biometric authentication.
A detective has been granted access to private consumer DNA data database
Update: DNA testing firm 23andMe has announced that DNA testing has decreased significantly due to a variety of factors including Privacy concerns and Law Enforcement requests. 23AndMe says it must comply with government subpoenas and does not inform the user of such when the court order requires it.