Why did Mama call Walter a disgrace to his father's memory?

Ruth says that she is going to abort their child, and Walter refuses to attempt to change her mind. Mama wants Walter to stand up and take responsibility for his family, she wants him to stop his wife and give her a reason to keep their child.

"Well — son, I’m waiting to hear you say something … (She waits) I’m waiting to hear how you be your father’s son. Be the man he was … (Pause. The silence shouts) Your wife say she going to destroy your child. And I’m waiting to hear you talk like him and say we a people who give children life, not who destroys them—(She rises) I’m waiting to see you stand up and look like your daddy and say we done give up one baby to poverty and that we ain’t going to

give up nary another one … I’m waiting."