Ziggy is the son of the creator of the automats called Norma Jeans.
Ziggy is actually an automat himself, created to hide the fact that his father killed him because of his aversion to Ziggy's "lifestyle". He has all of original Ziggy's memories and feelings, including his desire for revenge.
It's heavily implied that the so-called "lifestyle" that Ziggy's father hated was homosexuality, as Ziggy is shown naked in bed with another man in a page of the manga.
