"That's so weird," 9S insists, hardly mollified by the response. "I thought personality is something people are born with. That's sort of how it works for us."

And androids are modelled after humans, with so many of their traits mimicking their human creators, even down to the synaptic responses in their mechanical brains to mirror the synaptic responses in the humans' biological ones.

"I was created with the Number 9 personality type, so that's why I'm the way I am. Not because I'm 'young'. 2B isn't much older," he thinks, anyway; she can only be a few years older than him at most, "but she's toootally different. Sometimes she's ice cold!"