In contrast, children born in another country will adopt more easily than their parents. However, these children can gain mostly everything and become citizen of the new country, they will still keep some kind of experience of the life that gained in the old country. They might miss something left behind as well as they can go back if they want. Therefore, Rumbaut may thinks that these children can not fully represent new generation of immigrants.
Furthemore, children born in the new country can represent new generation of immigrants because they were born and raised in the new country, and they think of the new country as their homeland. They possess everything from society and become real citizens of the new country.