We went to Disneyland—Rosie, Phil, and I. It was great fun and appeared to be a success in improving all relationships. Rosie and Phil shared information and I learned a lot about Rosie’s life. It was important background for the difficult but essential task of developing a high level of empathy for one person in the world.

Rosie and I were on our way to New York, where being weird is acceptable. at is a simplification of the rationale: in reality what was important for me was to be able to make a new start with my new skills, new approach, and new partner, without being held back by others’ perceptions of me—perceptions that I had not only deserved but encouraged.

Here in New York, I am working in the Department of Genetics at Columbia University, and Rosie is in the first year of the Doctor of Medicine program. I am contributing to Simon Lefebvre’s research project remotely, as he insisted on it as a condition of providing funding. I consider it a form of moral payback for using the university’s equipment for the Father Project.

We have an apartment in Williamsburg, not far from the Eslers, whom we visit regularly. e Cellar Interrogation is now a story that Isaac and I tell on social occasions.

We are considering reproducing (or, as I would say in a social encounter, “having children”). In order to prepare for this possibility, Rosie has ceased smoking, and we have reduced our alcohol intake. Fortunately we have numerous other activities to distract us from these addictive behaviors. Rosie and I work in a cocktail bar together three evenings a week. It is

exhausting at times but social and fun, and it supplements my academic salary.

We listen to music. I have revised my approach to Bach and am no longer trying to follow individual notes. e new approach is more successful, but my music tastes seem to have been locked in in my teens. As a result of my failing to make my own selections at that time, my preferences are those of my father. I can advance a well-reasoned argument that nothing worth listening to was recorded after 1972. Rosie and I have that argument frequently. I cook but reserve the meals of the Standardized Meal System for dinner parties.

We are officially married. Although I had performed the romantic ritual with the ring, I did not expect Rosie, as a modern feminist, to want to actually get married. e term wife in Wife Project had always meant “female life partner.” But she decided that she should have “one relationship in my life that was what it was supposed to be.” at included monogamy and permanence. An excellent outcome.

I am able to hug Rosie. is was the issue that caused me the most fear after she agreed to live with me. I generally find body contact unpleasant, but sex is an obvious exception. Sex solved the body contact problem. We are now also able to hug without having sex, which is obviously convenient at times.

Once a week, in order to deal with the demands of living with another person, and to continue to improve my skills in this sphere, I spend an evening in therapy. is is a small joke: my “therapist” is Dave, and I provide reciprocal services to him. Dave is also married, and considering that I am supposedly wired differently, our challenges are surprisingly similar. He sometimes brings male friends and colleagues from work, where he is a refrigeration engineer. We are all Yankees fans.

For some time, Rosie did not mention the Father Project. I attributed this to the improved relationship with Phil and the distraction of other activities. But in the background, I was processing some new information.

At the wedding, Dr. Eamonn Hughes, the first person we had tested, had asked to speak to me privately.

“ere’s something you should know,” he said. “About Rosie’s father.”

It seemed entirely plausible that Rosie’s mother’s closest friend from medical school would know who he was. Perhaps we had only needed to ask. But Eamonn was referring to something else. He pointed to Phil.

“Phil’s been a bit of a screwup with Rosie.”

So it wasn’t only Rosie who thought Phil was a poor parent. “You know about the car accident?”

I nodded, although I had no detailed information. Rosie had made it clear that she did not want to discuss it.

“Bernadette was driving because Phil had been drinking.” I had deduced that Phil was in the car.

“Phil got out, with a broken pelvis, and pulled Rosie out.” Eamonn paused. He was obviously distressed. “He pulled Rosie out first.”

is was truly an awful scenario, but as a geneticist my immediate thought was of course. Phil’s behavior, in pain and under extreme pressure, would surely have been instinctual. Such life-and-death situations occur regularly in the animal kingdom and Phil’s choice was in line with theory and experimental results. While he had presumably revisited that moment many times in his mind, and his later feelings toward Rosie may have been severely affected by it, his actions were consistent with the primitive drive to protect the carrier of his genes.

It was only later that I realized my obvious error. As Rosie was not Phil’s biological daughter, such instincts would not have been applicable. I spent some time reflecting on the possible explanations for his behavior. I did not share my thoughts or the hypothesis I formed.

When I was established at Columbia, I requested permission to use the DNA-testing facilities for a private investigation. ey were willing to let me do so. It would not have been a problem if they had refused. I could have sent my remaining samples to a commercial laboratory and paid a few hundred dollars for the tests. is option had been available to Rosie from the beginning of the Father Project. It is now obvious to me that I did not alert Rosie to it because I was subconsciously interested in a relationship with her even then. Amazing!

I did not tell Rosie about the test. One day I just packed my bag with the samples that I had brought with me to New York.

I started with the paranoid plastic surgeon, Freyberg, who was the least likely candidate in my assessment. A green-eyed father was not impossible, but there was no other evidence making him more probable than any of the previous candidates. His reluctance to send me a blood sample was explained by his being a generally suspicious and unhelpful person. My prediction was correct.

I loaded Esler’s specimen, a swab from a fork that had traveled more than halfway around the world and back again. In his darkened basement, I had been certain he was Rosie’s father. But afterward I had come to the conclusion that he could have been protecting a friend or the memory of a friend. I wondered if Esler’s decision to become a psychiatrist had been influenced by the suicide of the best man at his wedding, Geoffrey Case.

I tested the sample. Isaac Esler was not Rosie’s father.

I picked up Gene’s sample. My best friend. He was working hard on his marriage. e map had been removed from his wall when I went in to submit my resignation to the Dean. But I had no recollection of seeing a pin in Ireland, Rosie’s mother’s birthplace. ere was no need to test the table napkin. I tossed it in the waste basket.

I had now eliminated every candidate except Geoffrey Case. Isaac Esler had told me that he knew who Rosie’s father was and that he was sworn to secrecy. Did Rosie’s mother—and Esler—not want Rosie to know that there was a family history of suicide? Or perhaps a genetic predisposition to mental illness? Or that Geoffrey Case had possibly killed himself in the wake of the news that he was Rosie’s father and that her mother had decided to remain with Phil? ese were all good reasons—good enough that I considered it highly likely that Rosie’s mother’s one-night encounter had been with Geoffrey Case.

I reached into my bag and pulled out the DNA sample that fate had delivered to me without Rosie’s knowledge. I was now almost certain that it would confirm my hypothesis as to her paternity.

I cut a small portion of the cloth, poured over the reagent, and let it sit for a few minutes. As I watched the fabric in the clear solution and mentally reviewed the Father Project, I became more and more confident in my prediction. I decided that Rosie should join me for this result, regardless of whether I was right or wrong. I texted her. She was on campus and arrived a few minutes later. She immediately realized what I was doing.

I put the processed sample in the machine and waited while the analysis proceeded. We watched the computer screen together until the result came up. After all the blood collecting, cheek swabbing, cocktail shaking, wall climbing, glass collecting, flying, driving, proposal writing, urine mopping, cup stealing, fork wiping, tissue retrieving, toothbrush stealing, hairbrush cleaning, and tear wiping, we had a match.

Rosie had wanted to know who her biological father was. Her mother had wanted the identity of the man she had sex with, perhaps only once, on an occasion of emotion-driven rule breaking, to remain a secret forever. I could now fulfill both of their wishes.

I showed her the remains of the blood-stained shirt from Jarman’s Gym with the sample square cut out of it. ere would be no need to test the handkerchief that had wiped Margaret Case’s tears.

Ultimately, the entire father problem was caused by Gene. He almost certainly taught the medical students an oversimplified model of the inheritance of common traits. If Rosie’s mother had known that eye color was not a reliable indicator of paternity and organized a DNA test to confirm her suspicions, there would have been no Father Project, no Great Cocktail Night, no New York Adventure, no Reform Don Project—and no Rosie Project. Had it not been for this unscheduled series of events, her daughter and I would not have fallen in love. And I would still be eating lobster every Tuesday night.

Incredible.