The Birth of Esau and Jacob & Isaac's "Sister" Rebekah

As the Genesis narrative transitions to Isaac (and quickly moves straight to Jacob), his genealogy includes the story of the birth of his twins; which sets up how the covenant continues through Jacob.

Isaac's story revolves around being in Garar with Abimelech (now of the Philistines) where he says Rebekah is his sister. This partly portrays Isaac as a continuation of Abraham and partly leads us to wonder how the covenant will continue through his two sons.