Frank Sinatra's Friend Believes Singer Was Not Ronan Farrow's Father: 'He Would Have Acknowledged Him'

When Tony Oppedisano began to write about his close friend Frank Sinatra, he wanted to show the music legend's human side. "I wanted the world to get a peek at the man that very few people knew," he tells PEOPLE. "A man I was fortunate enough to know and become very close to."

Among the stories he shares in his new memoir Sinatra and Me: In The Wee Small Hours, excerpted in this week's PEOPLE, is that of the singer's lasting friendship with Mia Farrow after their marriage ended in 1968. He addresses the curiosity of whether they remained romantically involved and if Sinatra could have been Ronan Farrow's father, a theory which made headlines in 2013 when Mia was asked point blank in a Vanity Fair interview if Sinatra could be Ronan's father. She answered in one word: "Possibly."

Ronan is Mia's son, born almost two decades after her divorce from Sinatra, at a time when Mia was in a relationship with Woody Allen. In 2018, Allen cast some doubt on whether he's Ronan's father, telling New York Magazine, "In my opinion, he's my child. I think he is, but I wouldn't bet my life on it."

"There's been a lot of gossip about Frank's possibly being Ronan's biological father," Oppedisano writes, "rumors I believe I'm a position to tamp down."

As he explains, Sinatra and Mia remained friends after their two-year marriage ended. Oppedisano even arranged for an under the radar visit in 1992 between the two at the Waldorf Astoria when Sinatra was staying there. "When she was beginning to have problems with Woody [Allen] she was looking for some comfort and it was like two old friends catching up," he says. "She was devastated and he was there to support her."

Furthermore, he conclues that Sinatra's health issues would have made it close to impossible for him to have been Ronan's father. Sinatra had emergency diverticulitis surgery in late 1986. Afterwards, Oppedisano writes, Sinatra "had to wear a colostomy bag until he fully recovered."

In addition, Oppedisano matches Ronan's Dec. 19, 1987 birthday against Sinatra's calendar, and says the singer's schedule would have also made it nearly impossible.

"There are only two ways Frank could have fathered Ronan, both absurd," he writes. "Either Mia made a secret trip to shack up with Frank in his California home with [fourth wife] Barbara present, or Frank, wearing his aways romantic colostomy bag, made a quick trip to Connecticut between his Atlantic City performances."

Most of all, he stresses, that wasn't Sinatra's way. "If Ronan had been Frank's son, Frank would have acknowledged him," he writes.

When asked about the rumor at the time of the 2013 Vanity Fair article, Ronan told Vulture, "You know, that story has been out there for years. It was somewhat surprising to see it break in such a huge way of late... I appreciate how hilarious it is. I mean, it's a ridiculous situation. That said, I'm pretty unfazed by it in substance, because it's been out there both publicly and privately for so long. You know, I have a relationship that I'm very happy with, you know, with all parties involved. For me, the imperative is 'all right, we've talked about it, I get a kick out of it, everyone gets a kick out of it."

As for the physical resemblance between Ronan and Sinatra, Oppedisano says, "People say, 'Take a look at [Ronan]' and I say, 'Well, take a look at Mia at the same age.' They look like twins. I've got blue eyes too and I'm not Frank's son."

The story is just one of many revealing and intimate stories Oppedisano shares in his memoir of their friendship, out on June 8. "I felt the world needed to know the man," he says. "He wanted someone to understand — and remember."