Steve Glazer who has done a lot of research and is a constant contributor to this website noticed the many mis-spellings. He writes:
"The recent discovery of Shep's jazz interview in the November 1955 issue of Playboy prompted me to gather all the variants of his name -- Jean Parker Shepherd, Jr. -- that have appeared in credible publications over the years.
Here are those I have gathered so far". . .
Jean P. Shepherd
Jean Kenneth Shefherd
Jean Peter Shepherd
Gean Peter Shepherd
And my personal favorite (perhaps influenced by Daphne?) . . .
Jean Barker Shepherd