Gu Yang didn't hesitate. "Hair. The paternity test was done secretly by the Tong siblings. Since Tong Jiayin was in the same dormitory as me, she must have picked up the hair from the trash can."
Gu Jin guessed that it was indeed hair.
Hair is the easiest sample to collect, but it's also the easiest to mix up. Noticing Gu Yang's last sentence, Gu Jin asked, "Did she ever pull out your hair?"
Gu Yang shook her head. "I wasn't familiar with her, so she didn't have the chance to pull my hair."
Seeing the concern on Gu Jin's face, Gu Yang asked, "What's wrong? Do I need to pull out my own hair for a paternity test?"
Gu Jin nodded. "For accuracy, paternity tests usually require hair with a follicle, so plucked hair is preferred. However, hair that naturally falls out can also be used if it has a follicle and hasn't been shed too long."
Gu Yang understood but was puzzled. "In my memory, no one has pulled out my hair."
