Born in the bustling metropolis of New York City, McKean made his grand entrance at Manhattan Women's Hospital, a facility that is now an integral part of the renowned Mt. Sinai St. Luke's complex, situated conveniently on Amsterdam Avenue.
As the son of Ruth Stewart McKean, a dedicated librarian, and Gilbert S. McKean, one of the visionary founders of Decca Records, McKean's early life was marked by a rich cultural heritage. His family's diverse ancestry, comprising Irish, English, Scottish, and a dash of German and Dutch, would later influence his artistic pursuits.
After completing his high school education in 1965, McKean embarked on a musical journey that would take him to the vibrant city of New York. In the early months of 1967, he briefly joined the "baroque pop" band The Left Banke, based in New York City. During his tenure with the group, McKean contributed to the recording of the single "Ivy, Ivy," with the B-side "And Suddenly" showcasing his musical talents.