Glenn Theodore Seaborg was born in Ishpeming, Michigan, on April 19, 1912, the son of Herman Theodore (Ted) and Selma Olivia Erickson Seaborg. He had one sister, Jeanette, who was two years younger. His family spoke Swedish at home. When Glenn Seaborg was a boy, the family moved to Los Angeles County, California, settling in a subdivision called Home Gardens, later annexed to the City of South Gate, California. About this time he changed the spelling of his first name from 'Glen' to "Glenn".
Seaborg kept a daily journal from 1927 until he suffered a stroke in 1998. As a youth, Seaborg was both a devoted sports fan and an avid movie buff. His mother encouraged him to become a bookkeeper as she felt his literary interests were impractical. He did not take an interest in science until his junior year when he was inspired by Dwight Logan Reid, a chemistry and physics teacher at David Starr Jordan High School in Watts.
Seaborg graduated from Jordan in 1929 at the top of his class and received a bachelor of arts (AB) degree in chemistry at the University of California, Los Angeles, in 1933. He worked his way through school as a stevedore and a laboratory assistant at Firestone. Seaborg received his PhD in chemistry at the University of California, Berkeley, in 1937 with a doctoral thesis on the "Interaction of Fast Neutrons with Lead", in which he coined the term "nuclear spallation".
Seaborg was a member of the professional chemistry fraternity Alpha Chi Sigma. As a graduate student in the 1930s Seaborg performed wet chemistry research for his advisor Gilbert Newton Lewis, and published three papers with him on the theory of acids and bases. Seaborg studied the text Applied Radiochemistry by Otto Hahn, of the Kaiser Wilhelm Institute for Chemistry in Berlin, and it had a major impact on his developing interests as a research scientist. For several years, Seaborg conducted important research in artificial radioactivity using the Lawrence cyclotron at UC Berkeley. He was excited to learn from others that nuclear fission was possible—but also chagrined, as his own research might have led him to the same discovery.
Seaborg also became an expert in dealing with noted Berkeley physicist Robert Oppenheimer. Oppenheimer had a daunting reputation, and often answered a junior man's question before it had even been stated. Often the question answered was more profound than the one asked, but of little practical help. Seaborg learned to state his questions to Oppenheimer quickly and succinctly.