Marvel Whiteside Parsons is born in Los Angeles, California, to Marvel Parsons and Ruth Whiteside. His early life was marked by a privileged upbringing that was later strained due to his parents' separation. He displays an early fascination with science fiction, which fuels his dreams of space travel and exploration.

Driven by his passion for rocketry and largely self-taught, Parsons, along with his friends Ed Forman and Frank Malina, begins conducting amateur rocket experiments in the Arroyo Seco, a dry riverbed near Pasadena. These experiments, often dangerous and fueled by enthusiasm more than formal knowledge, laid the groundwork for future successes and attracted the attention of academic institutions.