It was easy to find the answer by having a DNA paternity testing.
However, the "man" on the phone must be sure that Gong Zhengyang was his son.
Yao Guanghui was still in shock, and didn't notice when the phone was hung up. He kept thinking about Gong Zhengyang.
His refusal to believe and accept it gradually became anger. He couldn't wait a second longer to question Gong Zhengyang for the reason, but managed to calm himself down in the end. Yao Guanghui was a sophisticated man after all, so he knew how to compose his face.
Gong Zhengyang and Yao Lihui weren't home yet, and Yao Guanghui decided to search for Gong Zhengyang's hair in their room.
Gong Zhengyang married into the Yao family, so he lived in the Yao family's house. The couple also had their own house, but they spent most of their time in the Yao family's spacious house.
Yao Guanghui lived on the second floor, while Gong Zhengyang and Yao Guanghui's room was on the third floor.