Kim Jong-Un was the second of three children Ko Yong-hui bore to Kim Jong-il; his elder brother Kim Jong-chul was born in 1981, while his younger sister, Kim Yo-jong, is believed to have been born in 1987.
Kim Jong-Un ishte i dyti i tre fëmijëve të Ko Yong-hui dhe diktatorit Kim Xhong-il; vëllai i tij më i madh Kim Xhong-çul lindi në vitin 1981, ndërsa motra e tij më e vogël, Kim Yo-jong, besohet të ketë lindur në vitin 1987.