Michael Ethan Shepley, born in August 1949, was the oldest of three children of Ethan A.H. Shepley, Jr. (1923-1991) and Virginia Hill (1927-2021), who married in 1947. The Shepleys were a prominent St. Louis family. Michael's father was an attorney and president of Boatman's Bancshares from 1969 to 1988. Ethan and Virginia Shepley divorced while Michael was in college. Ethan A.H. Shepley, Sr. (1896-1975), Michael's grandfather, was the chancellor of Washington University from 1953 to 1961 and the Republican candidate for Missouri governor in 1964.

Michael Shepley realized that he was gay as a young man but had a difficult time coming to terms with his sexual orientation. He attended St. Louis Country Day School but transferred to the Loomis School, a boarding school in Windsor, Connecticut, during his sophomore year. Shepley came out as gay in a letter to his family in 1967 before he graduated from high school. He entered Tufts University in the fall of 1967 and spent his junior year abroad in London (1969-1970). After college graduation in June 1971, Shepley returned to St. Louis and worked for a brief time at The Muny as a publicity assistant. Later in 1971, he moved to New York City where he became involved in gay activist circles. He befriended movement leaders such as Arthur Bell (1939-1984) and served as an editor with Bell on the pioneering publication Out. Shepley returned to the St. Louis area in 2016 and currently serves in a leadership role in Trinity Episcopal Church in the Central West End.