Yes, he has a half brother, Kim Jong Nam. Reportedly, Jong Nam was to be the heir apparent to Jong il but embarrassed his father and China when he was caught trying to enter Japan to go to Disneyland. He has lived in Macau, China and a European nation. Last I heard or read, there was an attempt upon Nam’s life. Scuttlebutt has it that China considers Nam to be the heir apparent if Jong Un fails or vacates the sceen for whatever reason.
good point. China may well be grooming that guy to take over. Maybe he likes the system in China, more “free” (more or less) economy without loosening political power.