Kang was born and raised in Irvine, California, to immigrant working-class parents of Korean descent. She received a Bachelor of Arts in English and Theater from Occidental College in Los Angeles, California in 1998, after which she had several short stories and poems published and also wrote a number of plays. She eventually returned to school, where she received a Master of Fine Arts degree in screenwriting from the University of Southern California. Her first job in the television industry came when she worked as an intern for the ABC medical drama series Grey's Anatomy and Private Practice.