WMG / Doctor Slump

Senbei was taught robotics by Dr. Gero

Both men are capable of designing androids that are insanely powerful. There's also their design quirks, such as Arale needing glasses, Android #19 being fat and Android #20 being old (I know that #20 is really Dr. Gero, but why wouldn't he at least make himself look younger?). Arale's childlike personality is also similar to Androids #17, #18 and #16, all of whom display childlike traits such as disobedience (#17), greed (#18) and short attention spans (#16).