Zen is the second child of his parents Craig McGrath and Heidi Chapman. Zen takes after Craig with his film career, as do his siblings Gulliver and Winta. Craig is a director, and clearly, his love of film has infected his children. Zen is the middle child, Gulliver is 24 and Winta is 17. While Zen inherited his love for cinema from his father he likely got his passion for the sciences from his mother Heidi, who's a neuroscientist as well as a creative.

Gulliver McGrath, his older brother, is well known from movies such as Hugo, Lincoln, and Dark Shadows. He's currently in his third year at the Western Australian Academy of Performing Arts. Zen's younger sister Winta acted alongside her older brother Gulliver in Aloft and Boys in the Trees. Winta most recently played Campion for 18 episodes in the series Raised by Wolves.

Needless to say, all of the children in this family can act and have had success, with Zen acting alongside Hugh Jackman and Laura Dern just the most recent instance.

Zen and his family are balancing their creative pursuits with their education and growing up to be successful actors. Zen's intense role of Nicholas in The Son was a lot for a young actor to go through, and he dove into his character, becoming riddled with anxiety and nervousness that affected him even after filming was through. While Gulliver prepares to move full time to London and Winta nears graduating high school, Zen has reinvigorated his passion for acting following one of his darker portrayals.