Tang Wanwan told Kong Hou that Zhao Rouman was actually the illegitimate daughter. In earlier years, Zhao's father was a playboy with many lovers outside, while the legitimate wife had no children. Zhao's father had the idea of having a child with one of his lovers, not caring which one. As a result, the only offspring was Zhao Rouman. It was only after this that Zhao's father got tested and realized the problem was his own.
Zhao's father thought he wouldn't have any children in his life, so he brought Zhao Rouman back to the Zhao Family, treating her as if she were born from the legitimate wife. But when Zhao Rouman turned eighteen, the legitimate wife got pregnant and gave birth to a son. This was tremendous news for the Zhao Family, but not so good for Zhao Rouman.
