<P> Finn debuted at age 12 but has aged over the course of the show and is now 16 . Finn sets off on magical random quests around the Land of Ooo . He would gladly fight or beat up anything evil, but would not harm anything good or "neutral" as shown in "The Enchiridion!" when he refused to squash an innocent ant . Having a strong moral code, Finn swore that he would help anyone in need and often performs heroic feats to save the day; however, starting after season 3, Finn's enthusiastic nature becomes more toned down as the series progresses, suggesting he is both maturing and developing as a character as he ages . As shown in "Memories of Boom Boom Mountain", Finn appears to have been abandoned in the woods during infancy . He reveals that he had made "boom boom"--a euphemism for defecation--on a large leaf, fallen on it, and lay there crying until Joshua and Margaret, Jake's parents, rescued him from the wilderness and took him in to raise him alongside Jake, who became like a brother to him . As such, Jake is also Finn's adoptive brother . In "Henchman", when Finn is asked about his parents, he says Jake told him that he came from a cabbage, in jest . In the episode "Susan Strong", Finn states that he knows nothing of his human parents or any other humans . He is one of the few characters in the series (along with Flame Princess) who ages regularly . According to the episode "The Vault", Finn has had a number of past lives . In "Red Starved" it is revealed that Finn is color blind, believing that an emerald was a ruby . </P> <P> In the Season 6 opener "Escape From the Citadel", Finn has lost half of his right arm, up to his elbow, from which a flower protruded . He later regains his arm, now as a prosthetic, in the episode "Breezy", only to lose it once more in the seventh series finale "Reboot" when his grass arm transforms itself into a humanoid, sentient being . In the Season 8 premiere episode "Two Swords", Finn gets fitted with a new robotic arm by Princess Bubblegum, to replace the missing arm . </P> <P> Finn is currently 16 as confirmed in the season 6 finale "The Comet" and the early season 8 episode "Wheels". At the beginning of the series, Finn was a 12 - year - old boy who is supposedly the only known human in the Land of Ooo . During the episode "Mystery Train", Finn turned 13; it has been stated that the episode first airing date (March 14) is Finn's birthday . After season 3 ended, Pendleton Ward stated in an interview that Finn was 14 . Finn was 15 years old in the second half of Season 5, according to Adam Muto . In the Season 6 finale, "The Comet", Finn reveals that he has reached 16 years of age . This means that unlike in many other cartoons where characters stay the same age or age through time skips, in Adventure Time time passes regularly . </P> <P> Until the episode "Betty", Finn was the only known human in the Land of Ooo . A common theory explaining the etymology of his name includes the French word "fin", meaning "end". Another possibility is that his name is Irish, Finn being a name of a mythological Irish hero, whose name is derived from "fionn", the Irish language word for blonde; Finn the Human is blonde as well . The cause for him being the last human is alluded to by Finn and many other characters as "The Great Mushroom War", which was a nuclear war that wiped out the majority of humanity . Up until the character "Susan Strong" is introduced, Finn believes that he has never met another human . When Finn encounters Susan Strong, the other members of Susan's tribe of "Hyoomen" are revealed to be mutants, and Susan's identity as a human or mutant was left ambiguous . In the episode "Beautopia", it was hinted upon that Susan may also be human, but was not confirmed at the time . However, in the Season 6 episode, "Dark Purple", Susan's hat was taken off, revealing that she is indeed human, but with a cybernetic implant on the left side of her head, which meant she was a cyborg . The businessmen that Finn meets in the "Business Time" episode are also human, though they have been mutated over time . In the episode "Her Parents", Lady Rainicorn's parents (Bob and Ethel) attempt to eat Finn because they thought they would never get the chance to eat one, as they believed humans were extinct . Finn's female counterpart Fionna the Human is a human living in the Land of Aaa, though it has no official name; however, she exists only in a parallel universe conceived by the Ice King, when he wrote a fanfiction based upon his life and experiences with Finn and Jake . There are many other characters in the show that appear to be human but have been confirmed to be humanoids or mutants . In the episode Be More, the character Moseph "Moe" Mastro Giovanni, who is the creator of BMO, appears to be a human, but is revealed that he has replaced most of his body parts (except the skin) with artificial ones, which makes him virtually a cyborg . In the episode "Betty," Betty Grof (known as Simon Petrikov's former fiancee) was brought from the past into Ooo, and later in "Escape From the Citadel" Finn's father, Martin, is introduced, making Finn no longer the last human . </P>

How old is finn in adventure time season 8