Concepts in The Ender's Game Series - Anton's Key

Anton's Key is a fictional genetic modification to human DNA. Though named after its inventor, a scientist named Anton, it primarily afflicts Julian 'Bean' Delphiki; over the course of the novels, he passes it on to four of his nine children.

"Anton's Key" unlocks unlimited brain growth and continual formation of new neurons, allowing the person access to the intellectual miracles of infancy (language acquisition, physical dexterity and all other forms of learning) throughout their entire life. Children with Anton's Key will be born prematurely, but, despite low birth weight and shorter gestation period, will not require the extra attention of normal "premie" babies. All normal human growth milestones are accelerated, including (but not limited to) toilet training, walking, talking and puberty (except for the growth spurt). The disadvantage of Anton's Key is that the body grows along with the brain, resulting in unstoppable giantism. The immense size of the body causes circulation difficulties for the heart, which must pump blood through a network of arteries and veins much larger than that intended by nature, and the subject will eventually experience death via congestive heart failure. The one known bearer of Anton's Key, Bean, was not expected to live past his twentieth birthday; however, the Shadow series ends before his death, with Bean taking three of his carrier children on a prolonged relativistic voyage. In Shadows in Flight Bean and his children discover an early Formic spaceship, and are able to discover a cure to the disease, putting growth on a normal pattern while retaining their mental gifts. However Bean had grown too large and died aboard the formic vessel

Some scientists within the story argue that, because Anton's Key requires two distinct and unrelated mutations and thus could never occur in nature, those who possess Anton's Key are actually a newly-created species. Whether or not this is true, carriers of the modification are still able to breed with normal Homo sapiens, as Bean does with Petra Arkanian.

Because Anton carried out the research for this human genetic modification at a time when such activity was illegal, he was inflicted with a Pavlovian mental ban, preventing him from thinking about the topic without suffering a panic attack. Despite this, Volescu managed to solicit the information from him and, by incorporating the modification into an embryo belonging to his brother and fertility-challenged sister-in-law, created Bean. Later, Anton was able to give Sister Carlotta, friend and mother-figure to Bean, information about Bean's condition; she passed the information on to Graff, and eventually Bean himself. She was also responsible for reuniting Bean with his mother and father, who (by coincidence) were the parents of Bean's best friend Nikolai Delphiki.