For although Roger's family had split so wide apart, between his three daughters there were still mysterious bonds reaching far back into nursery days.

And Deborah in deciding whether to marry Allan Baird was affected more than she was aware by the married lives of her sisters.

All she had seen in Laura's menage, all that she had ever observed in Edith's growing family, kept rising from time to time in her thoughts, as she vaguely tried to picture herself a wife and the mother of children.
So the family, with those subtle bonds from the past, began to press steadily closer and closer around this one unmarried daughter, and help her to make up her mind..