Frank Simpson

Francine Simpson (formerly Frank) is Homer's cousin, but what we know about him can only be pieced together from what Homer has said about him. In the episode "Lisa's First Word", while discussing the possibility of moving from their small apartment due to lack of space because of the arrival of Lisa, Homer says that Lisa can have Bart's room, and Bart will sleep with them until he's 21. Marge asks "Wouldn't that warp him?" And Homer replies, "My cousin Frank did it, and he was fine." He then adds that Frank became Francine in 1976, joined a cult, and that he thinks her name is 'Mother Shabubu' now.

It's possible that Frank/Francine/Mother Shabubu's last name is not Simpson, and that he/she is related to Homer on his Father's side. He is uncle of Bart, Lisa and Maggie Simpson. He is the father/mother of Stanley Simpson he is a son one of Abe's brothers.