"What blows my mind is how much it's continued and how much people still value the story," Myles von Trapp Derbyshire, 30, told ABC News. "And the people that I meet, how much it's affected their lives. It's great to be part of a story that's proven itself to be timeless."
Myles is the great-grandson of Maria von Trapp, one of the main, real-life inspirations for the movie, and believes her story "is about being strong and facing adversity head on."
The film also focuses on the family's musical gifts and occupation as traveling singers. Maria von Trapp, who died in 1987, was the matriarch of the Trapp Family Singers.
Since "The Sound of Music" is based on a true story, Myles recalls the times he would visit the actual Trapp Family Lodge in Stowe, Vermont, and how that family landmark came about.
"After they came to the U.S., they were broke, because they had to leave everything behind in Austria," Myles told ABC News. "They decided on Vermont, it reminded them most of Austria with the green mountains and all. They bought a farm and turned that into music camp."
While Myles may not have too many memories of his great-grandmother, his mother, Stephanie, 55, remembers Maria.
"She was my grandmother," she told ABC News. "[We would visit] once a year. We would go for a family trip to the Trapp Family Lodge, which was her house. It was a big deal, because we would get out of school early! And we'd have a ball."
With the von Trapp family being the inspiration for the Oscar-winning film, some elements were exaggerated for dramatic effect.
"The whole relationship with Rolf was added, that did not exist," he said of one of the von Trapp children having a relationship with a young Nazi in the movie. "He's a made-up character. My grandfather was actually the eldest child. So the relationship there with one of the Nazis didn't exist. They didn't climb every mountain, they hopped on a train to Italy when it came to the Nazis pursuing my great-grandfather."
He added, "The house itself [in Austria, which was a mansion in the film] was not this grand, huge thing. They lived very humbly for several years before they left Austria and came to the US. ... The personalities of Georg and Maria are also actually reversed.
“My great-grandfather was very sweet and kind, Maria was apparently very moody," he said, laughing.
Stephanie says Maria “wasn't your snugly grandmother, but she was fun. I'll never forget, she wanted to take us to the local soft serve ice cream place. She was trying to describe how tall the ice cream cone was and she was very excited. She took us in her convertible Volkswagen Karmann Ghia. We got ice cream and I just remember that was awesome.”
What the movie got exactly right was "they did sing, stuff about my great-grandfather Georg and him being a naval captain, and being knighted is all true."
Myles von Trapp Derbyshire
Myles doesn't remember the first time he saw it but has an amazing memento that he cherishes.
"There's a picture of me sitting on my grandfather's lap watching the movie when I was 4 years old," he said. "You can see Julie Andrews dancing through the mountains and me on his lap."
Stephanie von Trapp Derbyshire
Stephanie remembers, and though she's excited now, at 5 years old, she admits she "didn't get it."
"I remember going to the theater. I remember thinking, 'Why was this so special?' I didn't quite connect the fact that we were von Trapps and the people in the movie were von Trapps. I didn't get that," she said.