Patti Smith has revealed how she discovered the man who raised her was not her biological father.

The 77-year-old musician and writer, often described as the "godmother of punk," revisits her life and career in Bread of Angels, published on 4 November by Random House, saying the revelation about her dad changed her understanding of her family.

The book, which follows Patti's National Book Award-winning memoir Just Kids, traces her journey from childhood in Chicago to her years in music and motherhood.

It also includes the discovery, made through DNA testing, she was not fathered by the man she grew up calling her dad.

Speaking to People, Patti said the discovery caused her to rethink the story she had always believed.

She said: "I wasn't sure what to do with this information, because I wanted the book I was writing to be very truthful, and all of a sudden, I had a parallel truth.

"And I felt if I didn't write about it, then it felt like truth was compromised."

The revelation began with a conversation between Patti and her mother, Beverly, in 2002.

During what the singer described as her "daily call", Beverly mentioned having "a story about genetics" to share next time they met.

When Patti saw her mother again, Beverly had been hospitalised after a fall and could no longer remember the conversation.

Family speculation about Patti's parentage had existed for decades by that stage.

Her great-grandmother had suspected Patti was fathered by her mother's uncle, but the idea was "waved away" by her parents.

In 2012, Patti and her sister, Linda, took a DNA test and learned they were half-sisters.

Pattie writes in her book: "We wept. The results of our test put a great strain on my thought processes and for some time, I was unable to write."

Initially, she believed the rumours about her great-uncle were true, but further genetic testing showed otherwise.

She added in her book: "I had all but accepted the fact that I was fathered by my mother's Uncle Joe, and fully expected the results to confirm it."

Instead, an autosomal test revealed her paternal ancestry was "100 percent Ashkenazi".

The breakthrough came through Patti's eldest daughter - the child she placed for adoption at 20 and later reunited with. Together, they traced her family line online and found her biological father, a man named Sidney.

Patti said: "I knew he was my father before I saw his face."

She later learned from a cousin that Sidney had died young and that his widow lived into her 90s, though she died before they could meet.

Patti said the discovery prompted her to take two years off from working on Bread of Angels.

She added: "As I was expressing gratitude to anyone else, I wanted to acknowledge him.

"He's also someone that was barely remembered. He had no children… and he's not someone that would be remembered pretty much by anyone. So I wanted to rectify that."

She also reflected on her parents, Beverly and Grant, who raised her with openness.

Patti said: "I was brought up in such an open and humanist atmosphere that I know that my mother and father would appreciate that.

"I was sad to not be Grant's biological daughter. I was sad to only have my sister, Linda, as a half-sister, but in the end, it doesn't matter. Our love for each other, my love for my father, eclipses blood, and my love for my sister eclipses blood."

Reflecting on how her daughter helped uncover the truth, Patti quoted William Blake's The Tyger, saying: "Fearful symmetry.

"Symmetry in life can seem frightening or like fate has already designed everything.

"But in other ways, it can seem quite beautiful.

"My daughter… was the one who really helped.

"It was a lot of sleuthing, a lot of detective work, a lot of following different bloodlines. But in the end, we found the exact person. It's kind of a miracle, really."