Imagine you reported to a job interview, and your future boss asked you to spit into a cup. You don't have any strands of DNA that could produce a red hiring flag, so you get the job. The guy behind you, on the other hand, isn't so lucky. Although you're both the same in every respect, the other person has a DNA signature that your boss doesn't want.
This is an imaginary situation, of course. But frighteningly enough, it's conceivable. That's why U.S. lawmakers created "GINA" the Genetic Information Nondiscrimination Act. Under GINA, employers cannot make any kind of employment decisions based on the unique DNA signatures of an applicant.