Biological libido suppression chemical agents is becoming real

In 2063, astrophysicists on a climate change–ravaged Earth find a habitable planet. A scouting mission is sent, although the roughly 86-year flight means that only some of the original crew, expanded with their children and grandchildren, will reach the planet. The 30-person launch crew are bred on Earth through in vitro fertilisation (IVF) using genius donors, and live their infancy and childhood in isolation in order to help cope with spending their remaining lives mostly in flight. To shorten the wait for news back to Earth, the 30 are launched as preadolescents on the spaceship Humanitas; they are joined by adult program commander Richard, to guide them through the journey's early stage. The plan is for IVF to be performed when the crew turns 24, to be repeated on those offspring when they turn 24. During the tenth year of the flight, Christopher and Zac discover a chemical is added to everyone's food that suppresses the sex drive and pleasure response, keeping them docile and manageable. The pair stop taking the chemical, with their surging hormones driving them to become competitive, careless, and anxious to engage in sexual relations. Their crewmate Sela, who has trained as chief medical officer, is assaulted by one of the boys, which distresses female members of the crew as well as Richard. During a repair effort outside the Humanitas to address a failed Earth communication system, Richard is killed and a fire damages more ship systems. Christopher is voted the new chief officer, which upsets Zac, who then tells the others to stop ingesting the chemical. The mission descends into madness as many of the young men and women revert to their most primal state. A power hungry Zac tells the weak minded others that an alien killed Richard, and he will protect them, letting them eat all the (closely conserved) food they want. He convinces all but five to follow him rather than Christopher. Christopher and Sela, who have become a couple, find and repair a video disk that reveals Zac killed Richard and precipitated the further systems damage by turning on the electricity to the communications array while Richard was working on it. They show the others, but Zac convinces many that an alien is inhabiting one of them, which leads his followers to murder one of their own. Christopher inadvertently leads Zac to a weapons cache for their grandchildren to use on the planet. Three of the holdouts join Zac's mob, leaving only Christopher, Sela, and Phoebe to oppose Zac. One of Zac's mob kills Phoebe, but Sela kills him in return. She and Christopher eject Zac into space, and his followers acquiesce to living peacefully. Sela is voted chief officer. The crew permanently forgoes the suppression chemical and learn to manage their emotions. They fall in love and have children naturally rather than via the planned IVF. After another 76 years, Humanitas and its multi-generational crew arrive at the planet, which appears from orbit to be as Earth-like as hoped.