Sven Simpson is one of the earliest known Simpson ancestors and the earliest known member of the "original" Simpsons (the earliest known of the modern being Virgil Simpson). He was the husband of Claretta Ethridge. They had two children named Lambert and Rupert Simpson. He is pictured as the Great, Great, Great, Great, Great Grandfather of Homer, whom he heavily resembles. Despite this, if Abe's story about Virgil Simpson is true, that would mean Sven is not related to Homer at all, and instead being related to Hiram and Eliza's side of the family, the "original" Simpsons, also making him distantly related to the Van Houten Family via Eliza.
Behind the Laughter
Sven is a Scandinavian name. That might mean that the Simpsons are of Swedish, Dansih, or Norwegian descent.