Justin Daniel Brush was born in Las Vegas, Nevada to Erika Tamargo (Kaufman) and Bernard Brush, both of whom were casino dealers. Spending his time in high school with football, NJROTC, robotics, and Science Olympiad, Brush didn't discover acting until his first semester of college in a "Fundamentals of Acting" course. He graduated from the University of Puget Sound in Tacoma, Washington, with degrees in computer science and theatre.While in college, Brush wrote 2 screenplays. The first is a semi-autobiographical story loosely based on his experiences in his nationally ranked high school NJROTC program. The second is a spin-off of "Tropic Thunder", entitled "Les Grossman: The Pre-Sequel". He co-wrote this script with the real Les Grossman.