Childhood Brain Damage
A character's mental handicaps are caused by them (or others) harming their head/brain as a child.
A explanation for a character's eccentricity, ditziness, lack of intelligence, brashness, etc is for them (or others) to harm their head or as infant or child. A possible cause of this trope could be that they were accidentally dropped by their Alcoholic Parent, who had a little too much to drink. In some cases, they were actually pretty intelligent before the incident happened. One variation of this trope is that the character's mental deficiencies are not from a head injury but by them ingesting something harmful and toxic such as paint chips or alcohol. Another is that the brain damage was due to the character being deprived of something that's essential or substantial to having a relatively healthy body. If this trope is Played for Laughs, a character may jokingly or cheerily suggest to the others that a daft moment that another character (who usually has no disabilities and is mostly functional otherwise) just had was due to them injuring their head in their childhood. However, if it's Played for Drama and the character genuinely had head trauma in the past, it's used as a indication that the character was abused as a child or had a very dysfunctional childhood (they may also have a head deformity because of it). Related to Phlebotinum-Induced Stupidity, as this trope has a more realistic take on how the character lost some of their intelligence.
- A variation of the trope occurs with Martin Soap from The Punisher : We see the nurse dropping him on his head just after being born, but he doesn't end up with any mental handicap for it (it's just there to show the crap life shoves on him started very early and never let up).
- In The Goonies, it's implied that Sloth's deformity was caused by being dropped as a baby. When Ma Fratelli tries to calm him down by singing "Rock-a-bye Baby", Sloth reacts to the line "tbe baby will fall" as if it has unearthed Repressed Memories, precipitating his Heel–Face Turn.
- Shadow of a Doubt: The film implies that a brain injury suffered when he was hit by a car as a child is what caused Uncle Charlie's "problem".
- In Brave New World it's rumoured that Bernard Marx's eccentricities are caused by there having been too much alcohol in his blood-surrogate while he was being grown.
- In Of Mice and Men, George tells the ranch owner that Lennie was kicked in the head by a horse as a child to explain why he's mentally slow. Lennie has to ask George about it afterwards as he doesn't know whether it's true or not - George then says it's not true.
- In The Grapes of Wrath, Pa Joad blames himself for his son Noah's slowness as he delivered him with forceps which injured his head.
- Played for Laughs at one point in the Malloreon, when Garion comments that maybe his tendency to charge into dangerous situations without thinking about the danger is because his Aunt Pol dropped him on his head as a baby.
- The Soviet book Kingdom Of Crooked Mirrors briefly features a character who was dropped on his head as a child. Since then, he can only count to three.
- In The Elenium, the main characters met a secondary, clearly handicapped characters who was hit on the head when young by a cow.
- In Kenan & Kel, Kenan once implies that Kel's lack of common sense (and otherwise intelligence) was the result of him being dropped on his head as a child.
- The Fresh Prince of Bel-Air has a slight variation, when Will asks Carlton if he was deprived of oxygen.
- Married... with Children: had a flashback in which Kelly (The Ditz) was shown to be very intelligent as a young girl, until she hit her head during a car ride.
- Garfield: Jim Davis opens the comic's 20th anniversary book by claiming, "I was born July 28, 1945, in Marion, Indiana, and was promptly dropped on my head - which explains my lifelong desire to become a cartoonist."
- Played for Drama in The Longest Journey: April's dad was drunk and dropped her when he held her as a baby for the first time, causing a serious cranial trauma that took several years to heal, during which she couldn't walk or speak. Although she eventually grew up normal (as normal as a half-dragon Shifter can be, anyway), her father's repressed guilt over the incident resulted in her very strained relationship with him and eventually led to her running away from home before the start of the game.
- 8-Bit Theatre: Black Mage asks Fighter if he was dropped on his head a lot as a child, to which Fighter answers, "Maybe..." This is immediately followed by a flashback to Fighter's childhood, with young Fighter exclaiming how happy he is to have power lines in his back yard and plenty of paint chips to eat.
- A flashback in The Order of the Stick explains Elan being The Ditz as a result of his brother Nale continually Dope Slap-ing him when they were babies.
- Two Best Friends Play: In one episode, Matt's being more of a ditz than usual, so Pat asks him if he ate paint as a child. Matt immediately answers, "You mean wall candy?"
- In Dragonball Z Abridged, Goku fell on a rock head-first when he was still a child. And he's noticeably more ditzy and absent-minded than his canonic self.
- All Grown Up!, the sequel to Rugrats, mentions that Dil is so strange because Phil and Lil dropped him on his head when they were babies.
- On Regular Show, Mordecai and Rigby travel back in time and meet young Pops, acting lucid and sane, unlike the Cloud Cuckoolander he is in the present. Later during a car chase, they hit Pops, who then starts giggling like present-day Pops.
- One episode of The Simpsons reveals that Homer is an idiot because he stuck a crayon up his nose as a child and got it jammed into his brain.
- On Sponge Bob Square Pants it is often suggested that Patrick's stupidity is the result of frequent head injuries. In "Squidward the Unfriendly Ghost", Patrick mentions that he knows a lot about head injuries, then spaces out mid sentence. In "Big Pink Loser", SpongeBob tries to discourage Patrick from mimicing him by hitting himself with a hammer, to which Patrick responds, "I've been doing this way before I started copying you."
- In an episode of The Beatles, John sews the money from last night's concert into Ringo's pocket to keep it from getting lost.
John: There! Safe as in a mother's arms.Ringo: Me mother dropped me once.John: I know. That's why I didn't sew it in your hat.
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