When Harry has finished recounting the story of his experience in the Chamber of Secrets, and Dumbledore has dismissed everyone else from his office, he asks Harry to have a seat. He thanks Harry for the loyalty that called Fawkes to him in the Chamber, then opens the discussion up to Harry regarding his meeting with the teenage Tom Riddle–perhaps knowing or anticipating Harry’s anxieties about their similarities. Addressing Harry’s concerns, Dumbledore says, “It is our choices, Harry, that show what we truly are, far more than our abilities.”
The idea of choices determining one’s true nature, as opposed to abilities, is perhaps most easily considered through the lens of different creatures in the Wizarding World, as they have very different abilities and powers in accordance with their species. Werewolves, for example, can choose to take Wolfsbane Potion or isolate themselves during the full moon, and these choices can prevent them from harming anyone. Remus Lupin makes this choice, whereas Fenrir Greyback chooses to attack his victims even when the moon is not full, and he is in complete control. Firenze comes to Harry’s aid in the Forbidden Forest in his first year and turns his back on his herd when he chooses to work for Dumbledore; Bane scorns these choices, believing that it is not the place of centaurs to interfere with fate. The relationship between goblins and witches/wizards is historically fraught, particularly due to wizards’ refusal to share the privilege of wanded magic with them and the belief that many wizards are thieves of goblin-made items. Both Griphook and Gnarlak strike bargains with wizards (Harry and Tina/Newt, respectively) and then betray their ends of the deal. Griphook actually correctly anticipates Harry’s half-truth about returning the Sword of Gryffindor, which at least partially justifies his behavior, whereas Gnarlak just calls in MACUSA in an effort to profit from both Newt and MACUSA. Furthermore, while Dobby the house-elf longs for freedom and cherishes every day of it by lovingly caring for every sock and sweater he receives, Winky drowns her sorrows over being freed in butterbeer. Kreacher, too, makes choices with gut-wrenching consequences before eventually using his powers to help Harry in his quest to find Slytherin’s locket. Even Jacob Kowalski, a Muggle man who stumbles into a life-or-death situation, chooses to offer his assistance to his friends by punching Gnarlak and kicking down the door to Graves‘ office. Despite his lack of magical abilities, he chooses to be a hero.
House allegiance also helps a great deal to illustrate the power of choices. While Harry chooses to be a Gryffindor, setting him on a different path from young Tom Riddle, his son Albus–who fears being sorted into Slytherin but has just learned from his father that the Sorting Hat will allow him to choose Gryffindor–seems to choose to allow the Sorting Hat to place him in Slytherin with his new friend, if it feels that to be prudent. While Sirius Black chooses to shun his Slytherin heritage, befriend James Potter, and be a loyal Gryffindor, his younger brother Regulus follows the Slytherin path. Falling prey to Voldemort’s charisma, he becomes a Death Eater until his change of heart leads him to plant the fake locket Horcrux in the cave and die a hero’s death. Similarly, Draco Malfoy followed in his parents’ footsteps by becoming a Death Eater, but his choice not to kill Dumbledore on the Astronomy Tower leads Harry to an understanding of his fear and entrapment; when Harry chooses to save Draco’s life, he is able to tell Draco’s mother that her son is still alive, and she lies to Voldemort, saying that Harry is indeed dead from the Killing Curse. In contrast, Peter Pettigrew grows up as a Gryffindor but is enticed by Voldemort’s charisma to become a Death Eater and betray his friends, eventually also aiding Voldemort in his return to his physical body. When Peter betrays his friends in favor of seeking glory as Voldemort’s servant, Snape betrays Voldemort in an effort to mitigate his wrongdoings and serve a penance to Lily Potter nee Evans, whom he idolized more than he ever did Voldemort.
Albus Dumbledore, himself, makes pivotal decisions that may have inspired this quote–his choice not to pursue the Deathly Hallows with Grindelwald, his choice to defeat Grindelwald in battle, his choice not to become Minister for Magic, and his choices regarding when and how much information to disclose to Harry about his fated battle with Voldemort. He gives Harry his father’s Invisibility Cloak, which he knows to be one of the Deathly Hallows, during Harry’s first year at Hogwarts, but does not ever breathe a word to Harry about the existence of the three Deathly Hallows that could make one the Master of Death. Instead, believing Harry to be sufficiently disinterested in wielding such absolute power, he trusts Harry to choose whether to pursue the Hallows or the Horcruxes.
In conclusion, the power of choice is particularly evident in two scenarios. When those with different abilities or circumstances make an ethical or unethical choice, that choice shapes the arc of their lives and the judgment of their characters. When those with the same abilities or circumstances choose opposing paths, the dichotomy that forms will create an apparent split between good and evil. When Dumbledore speaks to Harry regarding his concerns about his similarities to Tom Riddle, he shows a fervent trust in Harry’s character and judgment, just as Harry has just shown him extreme loyalty and faith in the Chamber of Secrets. While on this occasion Dumbledore is referring specifically to Harry’s choice to be a Gryffindor instead of a Slytherin, which differentiates him from young Tom Riddle, he also understands from a long lifetime of experiences that people are full of surprises, both good and bad. Because sentient beings have free will, the circumstances of one’s birth do not necessarily predetermine the course of one’s life.