Gattaca

In the near future, a blood sample taken minutes after birth can tell you almost everything: your likely illnesses, your probable talents, even a rough estimate of how long you'll live. Parents who can afford it have their children's genes selected before implantation, screening out disease and weakness and building in strength, intelligence and good looks. These "valids" grow up to fill society's best jobs. Vincent, however, is conceived the natural way — a "faith birth" — and the hospital computer instantly predicts a high risk of a heart disorder and a life expectancy of around thirty years.

Vincent grows up an "in-valid" in a world that quietly discriminates on genetic grounds — a practice everyone calls illegal and no one takes seriously. His younger brother Anton, engineered for perfection, is always faster, always favoured. As boys, the two play a dare called "chicken," swimming out to sea as far as they can before turning back; astonishingly, Vincent keeps winning, refusing ever to hold anything back for the swim home. But wins in the water don't change the world on land: Vincent's dream of joining the space programme at the Gattaca Aerospace Corporation is closed to him. His genetic profile qualifies him only for menial work, however sharp his mind or fierce his ambition.

Determined to reach space, Vincent turns to a black-market broker who arranges an illegal trade: he will live and work as Jerome Eugene Morrow, a genetically "valid" former swimmer who won silver, not gold, and afterwards attempted suicide and was left paralysed. In exchange for money and company, the real Jerome supplies Vincent with an endless daily supply of his own blood, urine and skin — smuggled onto Vincent's body in tiny bags and pouches so that Gattaca's constant genetic checkpoints always read "Jerome," never Vincent.

The transformation is gruelling: leg-lengthening surgery, months of practising to write with his other hand, coloured contact lenses to match Jerome's eyes. It works. "Jerome" rises to become one of Gattaca's top navigators, preparing for a coveted mission to Titan, Saturn's largest moon. He falls for a colleague, Irene, who carries her own hidden imperfection — an elevated heart-disease risk that has quietly capped her own ambitions, even though by the world's standards she counts as "valid."

Days before launch, Gattaca's mission director is murdered, and a police sweep of the crime scene turns up a single stray eyelash — Vincent's own "in-valid" DNA, dropped inside a building he was never supposed to be able to enter. Detectives begin hunting for an intruder inside the company, and one of them turns out to be Anton, Vincent's own brother, now grown into a genetic-profiling detective. The net tightens daily around "Jerome."

It emerges that the director killed the administrator who had threatened to cancel the mission — Vincent was never the murderer, only the accidental suspect his own DNA implicated. Irene, meanwhile, works out the truth about who "Jerome" really is, and chooses to protect his secret rather than expose it. In a final confrontation in the sea, Anton challenges Vincent to one last round of "chicken" — and loses again, forcing Vincent to save his own drowning brother and finally explain the secret of every childhood victory: he never saved anything for the swim back.

On launch day, the company doctor — who has clearly suspected the truth for some time — lets "Jerome" board the shuttle to Titan anyway. As Vincent finally leaves Earth to live the life he was told he could never have, the real Jerome, his part in the deception now complete, takes his own life.

The film's embryo selection has a real-world counterpart: preimplantation genetic diagnosis (PGD). During IVF, doctors can biopsy a single cell from a very early embryo and test it for serious single-gene disorders, such as cystic fibrosis or Huntington's disease, before deciding which embryo to implant. This genuinely happens today, in fertility clinics, for couples at risk of passing on a specific serious illness.

What the film invents is the leap from "screen out disease" to "engineer perfection." Selecting embryos for traits like height, intelligence or eye colour — rather than avoiding a known illness — is far more restricted, and in many countries not permitted at all. And in 2018, the scientist He Jiankui shocked the world by claiming he had used the gene-editing tool CRISPR to alter human embryos before birth; the resulting births were widely condemned, and germline gene-editing of embryos remains illegal in the United States and most other countries specifically because of the risks Gattaca dramatises.

Here is the film's central exaggeration. Real genetic science increasingly relies on polygenic scores — statistical estimates built from thousands of genetic variants that each nudge a trait very slightly. For most complex traits — behaviour, personality, even most health risks — these scores are, at best, weak predictors: research consistently finds that genetics explains only a modest share of the outcome, while environment, upbringing, chance and effort explain the rest. A gene can raise or lower a probability; it essentially never guarantees an outcome the way Gattaca's blood test implies.

The film even makes this argument against itself. Vincent, statistically written off at birth, outperforms both his genetically "superior" brother and the flawless Jerome, who ends his own life despite his perfect genome. That's not just a nice ending — it's close to the real, well-supported scientific point: genes set probabilities, not certainties, and the gap between the two can be the story of a life.