Why is the ex-wife's son's eyes gray among the unannounced visitors?

The children in Secret Visitors have gray eyes because they are the children of Mr. Wang's foreign lover Roy. Mr. Wang is gay, but the well-known Wang family doesn't allow his heir to be gay, so he can't fight against the family. He can only abandon his lover Roy until Zhang Xiaoxue marries him and gives birth to Wang Chuqi through IVF.

Zhang Xiaoxue thought that she and Mr. Wang had a baby, but when the baby was born, she saw that the child's eyes were gray, and she knew that things were not that simple. Mr. Wang cheated her by replacing her sperm with Roy's when she was making a test tube. This is why Mr. Wang dotes on Wang Chuqi so much, because he is his beloved child. Although Mr. Wang and Roy can't be together, he raised Roy's children, just like their sons. Zhang Xiaoxue couldn't accept this fact and finally chose to commit suicide. Mr. Wang was also surprised when he learned the news. He didn't expect it to do so much harm to Zhang Xiaoxue. To this end, Mr. Wang left Zhang Xiaoxue's daughter, Wang Chutong, and kept him with him. Stepdaughter Wang Chuqi tried her best to scare and persuade her to go to the police station in order to win her stepfather's love. Until Wang Chuqi discovered that no matter what he did, he couldn't get the care of his stepfather, who couldn't even compare with his adopted son Chen Xiaoqi. Stepfather burned his own painting, and Wang Chuyun chose to end this "home", so he stabbed his stepfather and everything finally came out.