What is the family history of the Griffins?

Answer 1

Naturally this is all speculation since some of the relatives show are most likely fictitious.

Peter Griffin << Thelma Griffin + Mickey McFinnigan

Thelma Griffin << Josiah Griffin + Peter's Grandmother

Josiah Grffin << Osias Griffin + Peter's Great Grandmother

Osias Griffin << Ulysses S. Griffin + Peter's Great Great Grandmother

Ulysses S. Griffin << Thomas Griffin + Peter's G. G. G. Grandmother

Thomas Griffin << Nate Griffin's Son + Peter's G. G. G. G. Grandmother

Nate Griffin's Son << Nate Griffin + Lois Laura Bush Cheney Pewterschmidt