I saw part of this in class and thought it was very interesting.
Set in the future, in a time of "genetic discrimination," where the government hires people based solely on their DNA. Valids are people whose genetics are chosen before birth, ensuring that they are the "best of" their parents. In-Valids are people whose genetics are left up to chance. One man, an In-Valid whose younger brother is a Valid, desperately wants a job in space, but the best job he can get is as the janitor. He meets a Valid who used to have the protagonist's dream job, but broke his spine. The government doesn't know this, so the protagonist is able to trade identities with the crippled Valid, who supplies him with blood and urine samples to fool the System.