Ned was raised in New York City by two nihilistic beatniks (the pair closely resembled John Lennon and Yoko Ono ). Their refusal to discipline Ned and terrible parenting skills made him a childhood terror. He was eventually put on an experimental eight-month spanking therapy program (the University of Minnesota Spankological Protocol) which taught him to suppress all feelings of anger. This resulted in Ned bearing a lifelong hatred of his parents—one of only two things that he hates (the other being the line in the post office). Also, all of the family's board games contain no dice, as Ned believes that dice are "wicked" (see Beliefs). Rod says that they just move one space at a time, as it is "less fun that way!". However, in the episode, Lisa's First Word, one can clearly see Rod, Todd and Bart playing a board game with dice.
Ned Flanders is a graduate of Oral Roberts University (as seen when Homer stole his diploma) where he belonged to a fraternity.
At one point Ned Flanders became principal of Springfield Elementary School after Principal Seymour Skinner was fired, despite Ned's thorough lack of administrative skill and experience. Already a shaky establishment to begin with, the school fell apart even more so under Ned's rather lax approach to being principal, putting the whole place on the honor system instead of traditional punishment. Bart eventually decided to get Skinner reinstated, finding that there was no real challenge in pulling pranks under Ned's watch, since Ned didn't have Skinner's uptight personality for Bart to play off of. Ned was eventually fired after Superintendent Chalmers heard him making a prayer over the school intercom, which is not allowed in public schools.
During the course of the series, Ned has represented both the Devil and God. In The Treehouse of Horror IV special, Ned played the Devil/Satan/Prince of Darkness in the opening segment "The Devil & Homer Simpson" (explaining that "It's always the person you least expect") in which the Ned-Satan offers Homer a donut in return for his soul, but is thwarted in a court of law when it was revealed that Homer had already legally promised his soul to Marge when they got married. Later in the series, when Marge fantasizes about being Eve opposite Homer as Adam, Marge/Eve imagines Ned as God (God was never clearly seen, but his voice was certainly that of Ned, and 'God's' arm wore Ned's traditional green jumper).
In the first several episodes he appeared in, Ned seemed to have only one son.
There was a relative of Flanders who served in World War II. He was a superior to Sgt. Abe Simpson. (Note: When Abe threatened to report Pvt. Burns to Flanders, Abe indicates that his rank was commander, which is not a rank in the United States Army. The rank "Commander Flanders" was most likely used as a cute rhyme, which is typical for a Flanders).
Both Ned and his kids rarely if ever refer to his moustache as such, preferring nicknames such as "Nose Neighbor", "Mr. Tickles", "The Soup Strainer", "The Pushbroom", "Dr. Fuzzenstein", etc.
For some reason, he is very afraid to say the word "sex", even when there are no children in sight (he either spells it out or calls it "doodily").
Ned appears to be slightly taller than Homer, who is 6', which would make Ned somewhere between 6' and 6' 2".