Jimmy Carter did own a peanut farm that he inherited. 
 However at the time of his election he was a highly decorated Navy Captain Lieutenant with 17+ years in command after graduating from the Naval Academy.    He was also a nuclear officer and was responsible for a great deal of policy regarding the first generation of US nuclear submarines.
 He served as Governor of Georgia, a as a State Senator, and as a member (and president of his county Board of Education.

Of course, our current President was a Professor of Constitutional Law at one of the most respected universities in America, an elected Senator, and was highly regarded intellectually by his Ivy Leage professors and fellow students.

But George Bush was part owner of a baseball team, so Jenkins must be right...lol