In "the not-too-distant future", liberal eugenics is common and DNA plays the primary role in determining social class. Vincent Freeman is conceived and born without the aid of this technology. He has a high probability of developing mental disorders, is myopic, has a heart defect, and his projected life expectancy is only 30.2 years. His parents initially placed their faith in natural conception and now regret it; Vincent's younger brother, Anton, is conceived with the aid of genetic selection. Anton surpasses his older brother in many aspects including a game that they call "chicken": both swim out to sea, and the first to give up and swim back to shore is the loser. Anton always wins due to his superior physical stamina. Vincent dreams of a career in space but is constantly reminded of his genetic inferiority. Later as young adults Vincent challenges Anton to the game of chicken. This time it is Vincent who pulls ahead while Anton runs into trouble and begins to drown. Vincent saves him, then leaves home shortly thereafter.
Due to frequent screening, Vincent faces genetic discrimination and prejudice. The only way he can achieve his dream of becoming an astronaut is to become a "borrowed ladder", a person who impersonates a "valid" with a superior genetic profile. He assumes the identity of Jerome Eugene Morrow, a former swimming star with a genetic profile "second to none", who had been injured in a car accident, leaving him paralyzed from the waist down. Vincent "buys" Jerome's identity and uses his "valid" DNA in blood, hair, tissue, and urine samples to pass screening. To keep his identity hidden, he must meticulously groom and scrub down daily to remove his own genetic material and then dust himself with Jerome's. With Jerome's genetic profile Vincent gets accepted into the Gattaca Aerospace Corporation, the most prestigious spaceflight conglomerate, with a DNA test being the entire interview process. He becomes Gattaca's top celestial navigator and is selected for a manned spaceflight to Saturn's moon Titan. A week before Vincent is to leave on the one-year mission, one of Gattaca's administrators is found bludgeoned to death in his office. Police discover an eyelash of the real Vincent on the premises, making him the prime suspect. A paper cup used by Vincent is also found after he gave it to Caesar the cleaner.
In 2004, bioethicist James Hughes criticized the premise and influence of the film Gattaca, arguing that:
Astronaut-training programs are entirely justified in attempting to screen out people with heart problems for safety reasons
In the United States, people are already discriminated against by insurance companies on the basis of their propensities to disease despite the fact that genetic enhancement is not yet available
Rather than banning genetic testing or genetic enhancement, society needs genetic information privacy laws that allow justified forms of genetic testing and data aggregation, but forbid those that are judged to result in genetic discrimination (such as the U.S. Genetic Information Nondiscrimination Act signed into law on May 21, 2008). Citizens should then be able to make a complaint to the appropriate authority if they believe they have been discriminated against because of their genotype.