S1, E1: This week on “DNA Mate,” Hong Ji Yun, Yuk Jun Seo, and Kim Jung Eun meet their younger siblings. Ji Yun bickers with her little sister, Ju Hyun, since morning. Jun Seo meets his little brother, Jun Hee, who's also a career soldier. He goes to his brother's house for the first time. Jung Eun goes to catch small octopuses with her sister, Jung Min.