It need to answer the most important question about franchise . Those are my answers about those questions - What happened to Penny parents ? How Gadget received his Gadget augmentation ? How did Gadget ended in dr Claw bad books in the first place ? How is is that Penny is not sick and tired of keeping him save and is not fed up with his stupidity and incompetence ? How is it that dr. Claw being so intelligent and competent did not realise that Penny was the one who screwed up all of his plans ? Why Quimby and other law enforcement are so trustful to Gadget while it is obvious he is dumb as a box of rocks ?
Remember , it's my guess , but I try to make things logical . My guess is that Gadget was once an ordinary police inspector with the difference he WAS very competent , intelligent , cunning , and could distinguish an enemy from a friend . Since he was very effective in his job this eventually came for dr. Claw and other law enforcement authorities attention who started to watch him . The reason why Claw was so eager to kill him was that during that time it was he who had proven that Claw is the mastermind of many seemingly unconnected crimes , thus destroying dr. Claw curtain of misinformation thus enabling law enforcemennt from all of the world for both East and West to begun an effective fight against MAD . Claw then realised that if he could do that , then he could became his undoing since he did the job many others failed to do . But Claw was smart and knew that everyone had a weakness . Dr Claw seeked for that and he found it . Gadget greatest weakness was his family . His father , mother , brother and sister (Penny's mother ) . He understood that since he will do everything for them , then he will use it against him . One day Gadget was invited by his sister to celebrate Penny's first birthday . He came with his friend who was a MAD agent in disguise ( true one was killed ) . Since it was richly oiled party everyone was sleeping in the home . The reason why Gadget survived was because he was always eating fat stuff as security . His sister who was sober asked him to get some aspirin for next day . When he returned the fire killed already all of his family . Gadget was shocked and broken but when he heard Penny's screams , he broke into the house to save her . While he suffered injuries he would get over . He wrapped Penny to fire proof blanked and hide her deep in his arms to save her it but during escape MAD agent detonated the bomb which almost killed him . The rescue party found them . Because of Gadget sacrifice Penny did not suffer serious wounds but Gadget seemed to be done for . He would die , but up from nowhere came the USSR ambassador . He was noticed about this accident and offered help . If you ask why then the answer is simple . Gadget was hunting down MAD everywhere including the Eastern Bloc and USSR . In USSR he foiled Claw plan which could endanger the russian people (I am thinking what could it be ) . Ambassador told that soviets invented a unique augmentation which could save his live . It was very thorough augmentation which would replace injured or destroyed part of his body . Even though operation was successful Gadget suffered concussion and serious head damage which resulted in amnesia and loss of his skills and intelligence . Neverless he remembered that Penny was very important to him and that Dr. Claw is his greatest enemy . And that's how Gadget as we know was born .