Beauchamp, Ancestors of Hubert and Sophonsiba

Thinking about his legacy in Go Down, Moses, Ike refers to "the ones who sired the Beauchamp who sired Uncle Hubert and his Uncle Hubert's sister" (294). The locution is confusing, in part because "his Uncle Hubert's sister" is in fact Ike's mother, Sophonsiba, as one might expect him to acknowledge. And obviously "the ones who sired" doesn't imply two fathers, but a longer generation of 'sires,' who would include Ike's great-grandfather and earlier male ancestors.