In Big Man, episode 6, Kang Jin Ah(played by Jung So Min) realized that Kim Ji Hyuk(played by Kang Ji Hwan) was not her real brother.
Jin Ah was suspicious about Ji Hyuk, who suddenly appeared to be her brother. She noticed that he was born in 1984, and then remembered that her parents were away in America for Kang Sung Wook(played by Eom Hyo Seop)’s master’s course.
Jin Ah asked Choi Yoon Jung(played by Cha Hwa Yeon), “You were with dad when he was studying for master’s degree in America, right? Were you happy? Did you guys ever come back to Korea in between?” Yoon Jung replied, “That was one of the happiest times of my life. Your grandpa wanted your father to concentrate on studying so we stayed in America for the whole time.”
Jin Ah noticed that Ji Hyuk was not her real brother, went over to his house, pull out his hair and left. She asked her friend, who was doctor, and requested a gene test.