Okay so that baby is Yi yi's real baby because Jinyao exchanged their sperm ig to protect Rou rou. Rou rou is Jin's real son taken under Yi yi's care thinking that it was his biological son. That aunt who we thought was kind took Yi yi's sperm thinking that it was for Jinyao. That was the reason why Jin did all the investigation from the beginning of the chapters .
Okay so that baby is Yi yi's real baby because Jinyao exchanged their sperm ig to protect Rou rou. Rou rou is Jin's real son taken under Yi yi's care thinking that it was his biological son. That aunt who we thought was kind took Yi yi's sperm thinking that it was for Jinyao. That was the reason why Jin did all the investigation from the beginning of the chapters .