Costner's father's heritage originates with German immigrants to North Carolina in the 1700s, and he also has English, Irish, Scottish, and Welsh ancestry.
Kevin Michael Costner was born on January 18, 1955, in Lynwood, California, the United States, the third child of Bill Costner, a ditch digger and ultimately an electric line servicer for Southern California Edison, and Sharon Costner (née Tedrick), a welfare worker. His older brother, Dan, was born in 1950. A middle brother died at birth in 1953. His father's job required him to move regularly, which caused Kevin to feel like an Army kid, always the new kid at school, which led to him being a daydreamer. He has described spending his teenage years in various parts of California as his father's career progressed, as a period when he "lost a lot of confidence", having to make new friends often. As a teen, he sang in the Baptist church choir, wrote poetry, and took writing classes.