In the movie Gattaca, its a space agency that is supposed to be in the near future. At this agency, they are planning a trip to Saturn's moon Titan. In order to take the journey, you must have the right genetic makeup. Vincent Freeman wants badly to make the trip, but in Gattaca he is considered an "in-valid", which means he has defective genes. Vincent "switches" places with Jerome Morrow, right down to the nucleic acid. Vincent takes hair, blood, and urine samples from the real Jerome, to pass all of the required tests at Gattaca. Due to the fact that the real Jerome Morrow was crippled in some kind of accident, Jerome needs Vincent just as much as Vincent needs Jerome.
The scientific premise, like in most science-fiction movies, combines a mix of truth and fiction. In the movie, the alleles from parents are so chosen that the combination produces the optimal arrangement in terms of the child's genotype. But we know enough right now to realise that even in situations where there is a great degree of genetic predisposition, it is quite probable that that predisposition (positive or negative) is never realised. For more complex behavioural traits such as intelligence, aptitude test results would be a far better indicator than genetic makeup. In other words, any correlation people may find between a complex behavioural trait such as intelligence and genetics is for all practical purposes controlled by the environment, given the "edge of chaos" nature of such traits.
"What is disturbing about our genetic engineering capabilities today is no more disturbing than our medical engineering capabilities (and there are plenty of disturbing ramifications). The genetic component simply provides one additional way to discriminate in the real world, just as it is routinely done with age, sex, years of experience, education, and physical ability: Consider the physical and mental requirements for being an astronaut today, or even for admission to college. Information, of any sort, is a valuable commodity in this day and age, and the kind encoded in DNA is no exception. Humans naturally use information to discriminate. I would argue that for some of scenarios posited in Gattaca, the genetic information is far less reliable than physiological and psychological histories. "