This in my opinion was the beginning of his major spiral downward from being just a "rebellious youth" to becoming the "monster" that he was then perceived as, during his obsessive quest toward becoming a god.
"The massive tattooed creature before him had begun life as a tiny, precious infant... baby Zach curled up in a wicker bassinette... taking his first fumbling steps across Peter's study... learning to speak his first words. The fact that evil could spring from an innocent child in a loving family remained one of the paradoxes of the human soul,"
This goes to show how just because a child is born into a seemingly kind and caring family, that doesn't account for the child's OWN personal behavior and character.
