Keyboard predators: Southeast Asia's kids targeted by online pedophiles

If there are any therapists or psychologists among readers, I'd be interested to know what causes a person to become a pedophile. I'm genuinely curious about this sickness of the mind. Or maybe to a pedophile, it's not a sickness but a natural urge. Does anyone know? And also why are most pedophiles (I assume) males? Are there female pedophiles? We never seem to read stories about them.