What is Wang Lung's attitude towards his 3rd child in The Good Earth? Why?

In Chapter 7 of The Good Earth, Wang
Lung's third child is born to him and O-lan.  But this time, O-lan tells her husband not
to get excited because the child is a girl.  Hearing this news, Wang Lung is struck by
"a sense of evil."  He immediately thinks of all the trouble that has been caused in his
uncle's home over a girl, and he does not want such bad luck following his own family. 
Girl-children are not valued in the culture because they do not carry on the family
name, nor do they bring wealth to the family. 

Later, Wang
Lung and O-lan learn that this child is mentally retarded, and Wang Lung's heart softens
to her.  At the end of the story, Wang Lung chooses to live with this daughter and his
youngest wife because they give him peace in his house of
turmoil.