Their three children are Kim Jong-chul (born 1981), Kim Jong-un (born 1983), and Kim Yo-jong (born 1987).[26] He did not have children with his fourth partner, Kim Ok.[13] The two half-brothers Kim Jong-un and Kim Jong-nam never met, because of the ancient practice of raising potential successors separately.[30][31] From the early 1980s onward, Kim Jong-il dichotomized the Kim Family between its main, or central, branch (won kaji) and its side, or extraneous, branch (kyot kaji). The main branch referred to Kim Il-sung’s family with Kim Jong-suk and publicly included Kim Jong-il and Kim Kyong-hui. The side branch referred to Kim Il-sung’s family with Kim Sung-ae and included the three children from their marriage.[6]