I think it is fairer to say that Simpsons made "Family Guy" possible (and also Beavis & Butthead, King of the Hill, Ren & Stimpy, Dinosaurs, Duckman, The Critic, South Park), in other words, Simpsons opened up the field to the fact that there was an audience for animation, and that animation presented a freedom of art forms. But Family Guy and Major Dad are aimed at a different audience and are a different style than "Simpsons".