Mabeline "Mabel" Simpson is an ancestor of the Simpson family and the great-great-great grandmother of Homer Simpson. Mabel's first husband was Hiram Simpson (with whom she had one child, Eliza) and her second husband was Virgil (with whom she had another child, Abraham). She is also an ancestor of the Van Houten Family through Eliza's marriage to Milford Van Houten.
She and her family worked with the underground railroad, but when her husband Hiram betrayed their activities to the slave owning Colonel Burns, she fled with the runaway slave Virgil to Canada, meeting Abraham Lincoln along the way, who offered that she cover her conspicuous hair with his stovepipe top hat. Later, she legally divorced Hiram and married Virgil, who had proposed to her on a bridge marking the border between the United States and Canada. Since Virgil had no last name he took the surname "Simpson." Mabel and Virgil had one known child, Abraham, whom they presumably named after Abraham Lincoln and who himself is the presumed namesake of Abe "Grampa" Simpson, Mabel's great-great-grandchild. She is identical to Marge, which is strange, because Marge is a Simpson by marriage, so it doesn't make much sense.