Needy Baby, Greedy Baby is a psychology book written by Leonard's mother, Dr. Beverly Hofstadter. It is mentioned in "The Recombination Hypothesis". The book was written in 2012 by Leonard's mother. It was mentioned in the 100th episode while Raj, Howardand Sheldon are playing The Settlers of Catan. Howard asks why he is going out with Penny again and Sheldon suggests a hypothesis from Beverly Hofstader's book Needy Baby, Greedy Baby of Leonard being "attracted to a good-natured simpleton like Penny is because she is the opposite of his first romantic attachment, his mother." Leonard is perplexed and asks where he got that notion from. Sheldon tells him where and Leonard tells him it's not true. Sheldon tells him that if it's non-fiction, it's true.