12/05/2011 at 03:35 PM EST
This Christmas, moviegoers have Steven Spielberg's 15-year-old daughter to thank for inspiring her dad to adapt the Tony-winning play War Horse into a movie.
"My daughter [Destry] is a great companion to have tonight because I made this movie with her in mind," Spielberg, 64, told PEOPLE at the world premiere for the film in New York Sunday. "Ever since I showed her Black Stallion years ago, she said, 'You've got to make a movie with a horse in it,' so I did."
Destry, the youngest of seven children in the Spielberg family, is a competitive horse jumper who participates in international competitions. She shares the love of horses with her mom, actress Kate Capshaw, and they've been raising their own horses at home for years.
"I've been living with horses for about 15 years," said the Oscar-winning director, who also shares a home with a border terrier, Australian shepherd and three parrots. "We have eight on the property living with us. They are the most magnificent animals. So when I saw War Horse on stage, I was even more ready to tell the story."
At the War Horse screening Sunday, Spielberg was worried about the opinion of his most important critic.
"She's never seen War Horse so tonight’s a big test for the movie," he said of Destry. "She's going to be the judge. I have a responsibility to get this right for her."