William “Bill” Post was born on June 27, 1927, to Henry Post and Johanna Jongsta in Grand Rapids, Michigan. His parents were Dutch immigrants and his father worked as a truck driver, carrying out used ashes from coal furnaces. Post attended high school at Grand Rapids Christian High School. At age sixteen, Post washed trucks for Hekman Biscuit Company, a cookie company which would later become Keebler.