Do you inherit God's promises just by being born into the right family line?

Les explains from Romans 9 that those who are of Abraham are not all the seed of promise. Ishmael had offspring and Esau had offspring, and although genetically they were children of Abraham, spiritually speaking they were outside the covenant promises, because those promises could only go to the offspring of Isaac and Jacob and down that family tree. Les warns that Israel became puffed up and arrogant, thinking that being children of the covenant, the prophets, and the promises meant they had it made. But Paul blows them out of the saddle, saying they would not enter God's promises simply because they were in the right genealogy; they still had to enter in by faith. Romans 9:7 says, "Neither because they are the seed of Abraham are they all children." Ishmael's and Esau's offspring were children of Abraham, but not according to the promises, because it is in Isaac that the seed should be called, and that seed refers to Christ.