There is, of course, only one chosen nation. But Abraham Lincoln would call America 'an almost chosen nation' because he believed that America had a providential role to play in history, inspired by the example of God's ancient covenant people.
Jews bear children not only because the carnal election of Abraham must continue. For Jews, raising children is essential to living a rounded ethical life.
The election of the Jewish people is the result of God's falling in love with Abraham and founding a family with him.