Who was Jacob's Father?

There's a constant refrain in Parshat Vayetze: "the God of  your father, Abraham." It's just that the person who is stated to be the son is Jacob, not Isaac. The Parsha starts out with the famous scene on Mount Moriah with Jacob and the ladder: "And behold! Hashem was standing over him, and He said, "I am Hashem, God of Abraham your father and God of Isaac, the ground upon which.. (Artscroll Trans.)."

This notion, namely that Abraham is considered the father of Jacob, repeats itself under some very dire circumstances pertaining to Jacob. Laban is pursuing Jacob's slow-moving entourage, wives, children and livestock and catches up to him on Mount Gilead. Hashem revealed Himself to Laban the night prior, warning him not to lift a finger against Jacob, or anyone in his encampment. Laban has strip searched all of Jacobs' tents, and failed to find his idols (which Rachel had stolen); then, Jacob, fighting fire with fire says, "Had not the God of my father - the God of Abraham and the dread of Isaac - been with me, you would surely have now sent me away empty handed; God saw my wretchedness and the toil of my hands, so He admonished you last night."

And then, finally, after Laban climbs down from the tree and agrees to make a pact with Jacob to both save face and ensure what he saw as the wellbeing of his daughters, he says, "This mound shall be witness and the monument shall be witness that I may not cross over to you past this mound, nor may you cross over to me past this mound and this monument for evil. May the God of Abraham and the god of Nahor judge between us - the god of their father. And Jacob swore by the dread of his father Isaac."

Going back in time, Terach, Abraham's father, had two other sons. One was Haran, who died before Terach made the journey from Ur Kasdim to Charan, modern day Anatolia. Abraham took Haran's orphaned son, Lot with him, on their journey to Charan; Terach died in Charan, and then Abraham continued with Sarah his wife and Lot to Canaan, to the Plain of Moreh. Terach's third son, Nachor stayed behind in Aram Naharaim in the city of Nachor, marrying Haran's daugher, Milcah, who was also the sister of our matriarch, Abraham's wife, Sarah. 

Nachor's son was Betuel, who was the father or Laban, the father of Rachel and Leah. 

It is thus very clear that ideologically, the two parties, namely Abraham and Nachor, are at odds with each other. Nachor maintained his idolatrous ways, passing them down to Betuel and thus to Laban. 

When Jacob says, "Had not the God of my father - the God of Abraham.." protected me, he uses the very same refrain that Laban would best understand, Abraham, the father of monotheism, who clashed with the idolatrous ways of Terach, who parted from Nahor. And likewise, God, in steeling Jacob for his mission refers to Himself as the "God of Abraham your father." He, Hashem is telling Jacob, needs to be your guidepost, your beacon. Isaac, your biological father, never encountered these heretical forces, and their deception. Isaac never the land, and Laban never met him, and thus it is only natural that he would say to Jacob, "May the God of Abraham and the god of Nahor judge between us." What Rachel was doing was not playing by the rules; you don't turn someone away from idolatry by stealing their idols. Laban seeks his idols in Jacob's tent, arrogating and averring that it was his idols behind Jacob's success, or that Jacob - at least in part - needed the idolatrous forces represented by Nachor, which is why Jacob, in a moment of anger proclaims that the one in whose possession they are found shall not live. 

It would seem that this acrimony and stark difference in viewing the world as one commanded by idolatry, or monotheism, is what led Jacob at the very end of the Parsha to not allow his men to eat with Laban. He did not let them intermingle. First, Jacob instructed his "brothers," i.e. his sons, to prepare a fit eating place for Laban's men on the mound. Only after they saw to their accomodations did Jacob then prepare offerings, slaughtering a feast on Mount Gilead for his own sons.