Charles Addams, the creator of the macabre family, chose the name for the daughter specifically because of this rhyme.
A person who doesn't fit the "sunny" expectations of society (unlike Monday's "fair of face" or Tuesday's "full of grace"). Wednesday's Child Is Full of Woe
"Wednesday's Child Is Full of Woe" is a line from the traditional nursery rhyme first recorded in the mid-19th century as a way to predict a child’s character based on their birth day. Charles Addams, the creator of the macabre family,
Whether viewed as a gloomy omen or a badge of edgy individuality, the phrase remains one of the most enduring pieces of folklore in the English-speaking world. the creator of the macabre family