The late Bill Walsh, the brilliant former head coach of the San Francisco 49ers, grew up a very lonely child. Newsday columnist Bob Glauber joined "Good Morning Football" on Friday morning to discuss his new book, "Guts and Genius," which tells the story of former coaches Walsh, Joe Gibbs, and Bill Parcells.

Glauber shared a turning point in Walsh's life. The coaching legend's son, Craig Walsh, told him an impactful story from the head coach's youth.

Walsh had a pet duck when he was about 11 years old and living in Los Angeles, Glauber shared on-air. He would tend to the duck every day, feeding it and caring for it. One day Walsh came home, and the duck was missing. The parents would not answer him when he asked about the whereabouts of his beloved pet.

Walsh then entered the house and smells something cooking for dinner. It was the duck.

The incident wasn't some mistake that happened. It wasn't some misunderstanding.

"The father, he was an abusive father," Glauber said. "Bill Walsh grew up in an abusive home. It was horrifying (for Walsh)."

Craig Walsh told Glauber that was the moment that changed his father's life.

"[Craig] says, 'At that moment, something happened to my father. Just concrete formed in his stomach. He just realized these people aren't going to help me,'" Glauber explained. "When you're 11 years old, think about that. He was a very lonely child and kind of kept to himself in a lot of ways."

Glauber continues by explaining that moment was an epiphany for Walsh, who then knew he would have to do everything himself and shaped the type of person he became.

"It was a very important moment in trying to crystallize who Bill Walsh was," Glauber continued. "Very complicated man. Of the three coaches (discussed in the book), by far the most complicated. But brilliance and genius come out in different ways."

Click here to read about the book, "Guts and Genius," from its official listing on Amazon.