Rebekah has no excuse to deceive her husband Issac. God gave Rebekah a prophecy that the younger will rule over the older but what Rebekah failed to remember is God doesn't need our help to fulfill His promises. He will NEVER cause us to do anything evil to see that His promises come to pass. Jacob demonstrated by manipulating Esau out of his birthright that he understood the importance of receiving such a blessing for their father. We assume that because Jacob spent more time closer to the home and his mother that she had to have told Jacob what God told her. Because Jacob knew God's plans he should have allowed God to do His work in His time therefore he is as responsible as Rebekah is. Rebekah actually shows a lack of faith and trust in God by her actions.