Colin Farrell Shares the Touching Moment His Son with Special Needs Took His First Steps: 'It Was Humbling to See'

Colin Farrell is opening up about one of the most special moments of his life.

The 41-year-old actor, who stars in the dark drama The Killing of a Sacred Deer, stopped by the PEOPLE, Entertainment Weekly and InStyle studio at the Toronto International Film Festival with costar Nicole Kidman and director Yorgos Lanthimos.

Farrell, who plays a father given a terrible choice in the movie, shared a joyful story from his real life as a dad. “When James took his first steps a couple weeks short of his fourth birthday, it was pretty amazing and humbling to see,” Farrell says.

The actor’s firstborn son, who turns 14 next week, has a rare genetic disorder called Angelman syndrome, which causes motor and developmental disabilities, among other symptoms..

Farrell says that while any child taking their first steps is a momentous occasion, it meant even to him knowing his son worked hard to reach that milestone.

“People talk about the children taking the first step, it’s obviously a monumental moment and it’s been represented in film,” Farrell says. “But to be told your child may never take the first step and then see those first steps is just kind of a different sport all together.”

Farrell then jokingly tells Kidman to “beat that,” but she responds that her two youngest daughters with husband Keith Urban have put a gag order on telling stories about them.

“I’m not allowed to talk right now about my children because they’re becoming aware of what I say and it gets reported back to them so I’ve been silenced,” Kidman admits. “I’m just very, very proud of them and would love to be able to discuss them, but have been told to cut it out.”