One of the exciting and mysterious properties of human genetic information is that your DNA doesn't just store who you are, it stores who you could be. More than a simple "fingerprint" that encodes a unique identity, your genome provides a spectrum of probable personal futures but this knowledge could be used against you.
As individuals, increased knowledge of our genetic makeup has helped us to better understand our heritage and ethnic origins, revealed family members we never knew, and helped personalize medicine. But our genetic identities don't share the same legal protections as our medical records and there has been a lot of buzz lately about an individual's right to keep their genetic information to themselves.
Of course you'd want your doctor to know what diseases you may be at risk for but what about your insurance company? Giving your health insurance company access to your genetic information could drastically change how much you pay and life insurance companies may just not cover you at all. Basically, one gene could change the fate of your coverage.
Washington Post: Employees who decline genetic testing could face penalties under proposed bill
Genome.gov: Privacy in Genomics
LA Times: U.S. military practices genetic discrimination in denying benefits