Kasch was born in Santa Monica, California. He is of Scottish descent. He was raised in Ojai, California on a working ranch until the age of 13, when he moved to Camarillo, California. Both of Kasch's parents were actively involved in the arts. His father was an actor and writer of locally premiering plays, and his mother was a director and photographer. As his older brother, actor Max Kasch, began to experience success, the brothers competed for jobs; their success caused the entire Kasch family to leave Ojai and move to the more favorably located Camarillo.