In our application of Genesis 27, Jacob does not offer any reasons for obeying his mother except out of a sense of duty.  She is very insistent and her motive for planning this scheme is out of love for Jacob, her favored son. In the case of the binding of Isaac, the reason Abraham goes on this mission is given in 22:1 where God tests Abraham and his faith. The reason the sons of Jacob lied to Shechem and Hamor was that Shechem had defiled Dinah their sister (34:13).
In other examples, the motive is revealed out of sequence after the planning of the deception had reached an advanced stage, or not until the lie had already been told. Sarah lied “for she was afraid” (18:15), even though we are not told exactly what she feared. Abraham and Isaac admitted they had fear of being put to death. Laban was confronted by Jacob the morning after being with Lea and he gives cultural norms of their day that refused to give the younger before the first-born ( 29:26). There may have been other reasons that he believes will not be as acceptable as this one.
The lie.
As soon as Jacob comes into Isaac’s tent, Isaac seeks his identity by asking, “Who are you, my son?” Confronted with such a direct question, he has no choice but to lie if the scheme is carried out.  This is the most blatant lie in the Genesis account.  He says, ‘I am Esau thy firstborn; I have done according as thou badest me.” Less straightforward and not as blatant was Abraham who asked about Sarah and he said, “She is my sister” (26:7, some would deny that he lied because she was his sister). Then, in Genesis 18:15, Sarah denied, saying, “I laughed not.” The lie was motivated not just by fear but in hope that the mere bold insistence of the lie would convince the listener.
Sometimes the lie is more subtle. The liar is cool-headed enough to surround the lie with words designed to mislead the listener or at least give pause for the possibility of the words being accurate and true.  When Cain was asked about where Abel was, he didn’t say that he didn’t know, but instead distracted attention away from the question and an honest answer and say, “Am I my brother’s keeper?” (4:9). Similar in intent, Rebecca attempted to cover up the tension between her two sons by getting Isaac to agree to Jacob’s hasty journey to Haran. She says, “I am weary of my life because of the daughters of Heth: if Jacob take a wife of the daughters of Heth, such as these which are of the daughters of the land, what good shall my life do me”(27:46).  Also, compare Dinah’s brother’s lengthy statement of intent designed to confuse them.  It reads, “And they said unto them: ‘We cannot do this thing, to give our sister to one that is uncircumcised; for that were a reproach unto us: But in this will we consent unto you: If ye will be as we are, that every male of you be circumcised; Then will we give our daughters unto you, and we will take your daughters to us, and we will dwell with you, and we will become one people. But if ye will not hearken unto us, to be circumcised; then will we take our daughter, and we will be gone.’” (34:14-17).
An alternative tactics is to bend the truth by enhancing the facts. For example, the serpent adopts this former method when asking Eve: “Yea, hath God said, Ye shall not eat of every tree of the garden?” (3:1) He knew that God restricted them from eating just the tree of the knowledge of good and evil (2:16-17).  Another way to bend the truth is to downsize as when Abraham, who had been commanded to offer up Isaac as a sacrifice, informs his servants: ” I and the lad will go yonder and worship, and come again to you” (22:5).
Genesis 27 goes to great lengths to show that, when lying to his blind father, Jacob did not rely solely on word of mouth to ensure the deception’s success. Verbal communication, after all, could only influence whatever Isaac heard. In collusion with his mother, Jacob also sought to add conviction to his lie by tricking his father’s other sensory faculties:  his sense of taste by the provision of delicious food (22:9) his sense of touch by the use of goats’ skins; and his sense of smell by dressing Jacob in Esau’s best garments (22:30), and skins of the goat (22:31).
So, Adam attempts to deceive the Almighty by hiding “in the garden tree” (3:8); Lot’s daughters dull their father’s sensory judgment by filling him with wine so much so that when he was drunk, “the firstborn could go in, and lay with her father; and he perceived not when she lay down, nor when she arose” (19:33).  Lea conceals her true identity from Jacob on their wedding night  (Genesis 29: 25) and when fleeing his father-in-law, Jacob “stole away unawares to Laban the Syrian”(31:20) and Rachel deceives her father when hiding from him those of his idols that she had stolen (31:19+34).
Especially prominent, and frequently discussed, is the place of clothing and disguise at the heart of the lie.[36] In this context, too, Genesis 27 presents a detailed example. As already noted, Jacob uses goatskins and Esau’s clothes in order to adopt a false identity. Subsequently, Tamar dresses in the garments of a whore in order to mislead Judah (38:14). In both cases, clothes provide camouflage.[37]  Elsewhere, however, clothes are employed as false evidence, adduced in order to substantiate a false accusation. The veracity of all of the accusations leveled against Joseph by Potiphar’s wife (chapter 39) depends on the garment he left in her hands, [38]   just as the authenticity of the brothers’ suggestion that Joseph must have been devoured by a wild animal is backed up only by the evidence of his blood-soaked coat (37:33).