One way of explaining their weird and disturbing behavior — lack of social skills and boundaries, violent tempers, Arim's preoccupation with their looking alike, closets filled with nothing but trashy club clothes — could be that they're chronologically preteens. By this line of thinking, they were likely born unhealthy and could not have survived, and their father transplanted their brains into adult-size robot bodies to keep them alive. Their aloofness is that of children trapped in an adult world, and their fondness for provocative clothing is really nothing more than two little girls playing dressup.
WMG / Pulse
Mira and Arim, the cyborg twins, are actually children or young teenagers in grown-up robot bodies.