Don immediately texts Gene about meeting the next day to discuss what just happened with Rosie, but Gene pushes the meeting to Sunday morning—and asks for Bianca’s contact information. Don contemplates that Rosie clearly wanted to have sex with him, but he is confident that he made the right choice in declining. However, he also realizes that Rosie is a perfect candidate for noncommittal sex and becomes fascinated by a potential sexual relationship with her.

When Sunday arrives, Don decides to discuss his situation with Gene and Claudia simultaneously because their combined expertise—Claudia in counseling and Gene in sex—would efficiently help him solve his dilemma. However, he makes another unperceived error when he says aloud that he is counting on Don’s “extensive practical experience” (158) while Gene and Claudia’s son Carl enters the room. Gene tries to brush off the comment by saying he was much younger when this practical experience took place, but Claudia walks out. 

While having lunch, Gene tells Don that not telling Rosie she is beautiful was wrong but agrees that she’s ideal for a casual affair. When Don admits that he finds sex a bit complicated, Gene tells him to get a book on sexual positions. Don takes this advice immediately, leading to another awkward encounter with the dean as she enters his office while he’s using a skeleton to properly achieve one of the book’s positions. The dean has brought along Dr. Enticott, who was interested in offering a funding package for Don’s research. This interest is likely because Don and Dr. Enticott are already acquainted, having met when Don and Rosie were trying to get his DNA and then seeing each other again at the reunion. But Don rejects the money to the dean’s chagrin.

Following that impromptu meeting, Don seeks out Rosie in the psychology department. Stefan is present, and he begins teasing Don and Rosie about how popular their dancing had been. When he assumes that the two are dating, Rosie angrily corrects him. Don asks to speak with her privately, but she insists he can say whatever he wants right there. So, he says he has reconsidered her offer of sex. After a long silence, Rosie tells Don it was a joke. When he then asks when they can resume work on the other project, meaning the Father Project, she says “There is no other project” (162).

Don resumes his regular schedule for a week, but he is increasingly distracted by his last conversation with Rosie. He attempts to contact her several times, finally just leaving a message about how the Father Project must continue because there are only 11 potential fathers left to test. She does not respond. Claudia advises him to move on, but Don decides her advice does not apply to him because it is predicated on what an average person would do. He decides that resolving the Father Project on his own could help remedy the situation with Rosie. This means putting the Wife Project to the side once more, though he does update the questionnaire based on “the Bianca Disaster” (164).

Because everyone in the potential father pool is a doctor, Don thinks a ruse like the genealogical study lie he told to Dr. Hughes is the way to maximize results. He constructs a fake research project on the genetic markers of autism in high-achieving people and sends off the fake research questionnaires and cheek scrapers to the remaining father prospects. Seven of the remaining 11 respond. None of them is Rosie’s father. 

Of the candidates who have yet to submit a sample, two live in New York, one died shortly after Rosie was born, and one is Simon Lefebvre, head of the university’s Medical Research Institute. When Don calls Dr. Lefebvre’s office to solicit his sample, the professor insists on discussing it in person. During their meeting, Dr. Lefebvre repeatedly mentions someone named Charlie—revealed in Chapter 32 to be a nickname for the dean, whose first name is Charlotte—and then tells Don he will only give a sample once he receives all the official paperwork on the project. Don decides to write a full proposal on his fake study, spending hundreds of hours working on it, because he believes getting Simon’s sample is imperative, despite the low probability of him being Rosie’s father.

Don receives word that Daphne has died and left him $10,000, with the instruction to use the money for something irrational. Don decides to use the money to buy tickets for him and Rosie go to New York to get the two remaining samples.

He successfully obtains Dr. Lefebvre’s DNA sample when he delivers the proposal.

Don lurks for several days in the cafeteria where Rosie usually eats her lunch, waiting for his opportunity to tell her about his continuing work on the Father Project. She is astonished by the fact that Don is essentially risking his career to help her. He tells her about his plan to go to New York, which she dismisses as being too reckless a step. But Don piques her interest when he explains who the remaining three candidates are. During their conversation, they see Gene escorting Bianca to a private dining area. Don attempts to assuage Rosie’s distaste by relaying that Gene is doing research and that he and Claudia are in an open marriage. Rosie asks if Don would pursue an open marriage with whoever the Wife Project determines is his perfect partner. He says he would agree if it was what his wife wanted, but he would be satisfied having only the one sexual partner. Rosie then agrees to go to New York with him.

Don investigates the remaining family of Geoffrey Case, the potential father who died. He finds that Geoffrey’s widowed mother, Margaret, lives in a nursing home far from Melbourne. He decides to go see the woman alone. Being a doctor often allows him to skirt traditional gatekeeping rules in medical settings, so he knows he will have no issue gathering a sample from Margaret. On the drive, he thinks about the Father Project and considers the likelihood of Geoffrey Case being Rosie’s father.