What does it mean "spiritual"? Rebekah was not a priest, on the other hand, she consulted her problems with God. She believed in God, she trusted the God, she relied on the God. But was she "interested in spiritual things". I do not think so. And Isaac - he was more interested in hunting, but he prayed for her wife. Why? He wanted a son, a heir. It is similar as we are doing. We are praying mainly when we need something, when we miss something, when we are ill, poor. Are we so much different then Isaac and Rebekah? Up to now, I did not find any evidence of spirituality in Jacob or Esau. Mainly the reason is that both are young. As anyone of us, they have to grow, to attain maturity not in the physical sense but in the spiritual, intellectual sense.