Kit is strong-willed, independent, and used to getting attention. She becomes jealous when she feels that someone else is receiving attention that she expected to obtain for herself, particularly romantic attraction from a man. This tendency makes her jealous of Judith early in the story, before William turns his interest to Kit. Interestingly, Kit also sometimes envies her cousins for their practical abilities, since she was never trained to make porridge, sew dresses, or do anything to help fulfill the fundamental requirements of life.
Judith is practical, but also has secret longings for a life of leisure and for fancy possessions. Given her humble and religious upbringing, she is jealous of Kit for Kit's rich background and the beautiful clothing she brings with her from Barbados. In contrast to Kit's habit of romantic jealousy, Judith is not jealous about William for long, since she becomes attracted to John Holbrook fairly quickly.
Mercy, who is kind and loving, is the most self-sacrificing character in the book. She loves John Holbrook, but she would never choose to take him away from Judith. In fact, Judith and John almost end up engaged, but fortunately fate prevents that from happening. Mercy loves her sister and, while she may be sad at the idea of giving John up to her, there's no indication that she feels the uglier emotion of jealousy about the situation.