What does Rose mean by "You can't visit the sins of the father upon the child"? How does this line connect to the overall theme of the book?

Rose is referring to Troy's child and the need to take the infant in. The baby, a little girl, needs a family, the fact that her father committed adultery has no place in that decision. Rose, who is very religious, believes in the innocence of children.... her husband's sins have no bearing on that fact. Rose's act supports the themes of fences.... protecting the family.