In your culture you may need to place 9:11 after 9:12 to make them easier to understand. Alternate translation: "our father Isaac, it was said to her, 'The older will serve the younger.' Now the children were not yet born ... because of him who calls. It is just"
Paul refers to Isaac as "our father" because Isaac was the ancestor of Paul and of the Jewish believers in Rome. (See: [[rc://en/ta/man/translate/figs-inclusive]])