Gadget Boy and G-9 appear to switch between being fully robotic to being half robotic in different episodes. In #10, "Gadget Boy and the Uncommon Cold", it is revealed that Gadget Boy is half robot and thus catches a cold while G-9 does not. However, in #20, "Boy Power of Babble", Gadget Boy is unaffected by the "babblizer ray" because he is half robot with a mechanical brain, whereas G-9 is completely robotic. Don Adams voices Gadget Boy, similar to being the original voice of Inspector Gadget. Gadget Boy commonly says, "Sowsers! Bowsers!", similar to Inspector Gadget's catchphrase, "Wowsers!".
All of Inspector Gadget's gadgets except smaller.
He was conceived as a bionic "child" with the personality of a "perfect adult detective" (although as with the aforementioned Inspector Gadget, he is anything but). Like Inspector Gadget, Gadget Boy is equipped with gadgets in his body and is as clumsy as Gadget, but will use the gadgets to get himself out of sticky situations.
The bionic implants were installed by the inventor Myron Dabble. Agent Heather bails Gadget Boy out of danger, though he was also helped greatly by his myriad high-tech gadgets and extendable arms and legs. However, Gadget Boy is usually seen with Agent Heather and G9, unlike Gadget, who in the original series, will usually inform Penny and Brain once he receives his assignment that the mission is too dangerous and that he will be going on the mission alone, and usually be convinced that a disguised Brain is a M.A.D. agent.
It is unknown if he and Lt. Gadget are related or if they're the same person. Though, Gadget Boy and Inspector Gadget being robots, it's highly unlikely. Just like Lt. Gadget, he is voiced by Don Adams and Maurice LaMarche.