Nugent was born the third of four siblings in Redford, Michigan, and raised in metropolitan Detroit, Michigan, the son of Marion Dorothy (née Johnson) and Warren Henry Nugent. As a teenager, Nugent attended St. Viator High School in Arlington Heights, Illinois, and for a short time, William Fremd High School in Palatine, Illinois. His maternal grandparents were Swedish.
Nugent grew up in a military family; his father was a career army sergeant. Nugent himself never served in the military, even though he came of age during the height of the Vietnam War. In 1977 and 1990 interviews with High Times magazine and the Detroit Free Press, Nugent claimed he deliberately failed his draft physical by taking drugs, eating nothing but junk food for days beforehand, and defecating and urinating in his pants.
Nugent denied his defecation story in a 2018 appearance on The Joe Rogan Experience; he asserted that he invented the story for himself and his band's amusement, as he claimed news sources at the time often published inaccurate information on his band. He also stated he was eligible for military service and passed a draft physical in 1969 and received a student designation rather than a student deferment several months later while he was attending Oakland Community College, but was not called to service. Nugent further stated that his 4-F rating on Wikipedia was "made up," despite the fact that the article sourced it to snopes.
Nugent's Selective Service classification record shows he initially qualified for student deferments. When he was no longer enrolled in school, he received a draft rating of I-A, until he failed a draft physical on August 28, 1969. After that physical, he was rated 1-Y ("registrant qualified for service only in time of war or national emergency") until that classification was abolished in 1971. He was subsequently reclassified 4-F, indicating ineligibility for military service under established physical, mental, or moral standards.