Holman was born in Drammen in Buskerud County, Norway. He was the only child of Hans and Kirsten Halvorsen Guttormsen. His father was a successful businessman, and had a large estate called Holmen at nearby Konnerud, where he farmed minks, a weasel yielding precious fur. The family's affluence meant that Holman enjoyed a relatively comfortable upbringing—a contrast to the economic hardship endured by most Norwegians at that time. An illustrative curiosity is the fact that Holman's mother, Kirsten Halvorsen, was the first woman in the city to have a driver's licence. Holman came from a family of profoundly religious Christians, and it possibly imbued him with an acute spiritual awareness. Holman displayed early on that he was fitted with a powerful intellect and an inquisitive mind; he took a deep interest in music, but also pursued studies in mathematics, physics and chemistry. Holman was only 15 years old when Hitler's troops invaded Norway. Even though he was a mere teenager focusing on his education, it did not prevent him from becoming an active member of the underground resistance movement.