Julia Cuddy is the younger sister of Lisa Cuddy and younger of the two children of Arlene Cuddy. She is portrayed by actress Paula Marshall. Although she is mentioned throughout the series, she only appears in Season 7.
Unlike her career minded sister, Julia's life is focused on her husband and three children (Family Practice). Cuddy usually eats Thanksgiving dinner at her house (Ignorance is Bliss), but on that occasion used Julia as a decoy to make sure House didn't crash the dinner.
Julia appears for the first time in Family Practice, taking care of her mother during her illness. However, her presence causes problems when the team tries to be deceptive as Julia knows both Robert Chase and Eric Foreman, so they can't sneak into Arlene's room without being recognized. When Julia tries to stop Lisa from keeping Arlene at the hospital, Lisa threatens to have security arrest her.
Julia has a much closer relationship with Arlene than Lisa does, which upset Lisa until she realized Arlene knew when they were both young that she could accomplish much more than Julia and pushed her to achieve. That being said, although Arlene says she loves them both equally, she also admits she has much more in common with Julia.