Jing-Mei's mother clearly abandoned her babies because she felt she had no other choice. She may not have survived the journey, and even if she did, how would she care for them? She likely hoped they would be picked up and cared for by someone who could afford to feed them and give them a life that is not one of suffering and mysery.
Jing-Mei struggles with her identity especially knowing that her two sisters survived, because her mother always pushed her to be the best she could be despite her resistance. By resisting every suggestion of her mother, Jing-Mei made her only daughter "disappointing" and felt sad because perhaps her mother had wished for her other two daughters in exchange for Jing-Mei. She feels that perhaps her mother would have rather had two good, chinese daughters than Jing-Mei, and feels that her mother may have regretted the decision to leave them behind throughout her life. Jing-Mei also feels a struggle between being Chinese and being American; she never felt Chinese enough for her mother. Visiting China helped to resolve some of Jing-Mei's cultural issues because she realized that China has changed since her mother left it.