Which country in the world doesn't have its own mother tongue?

Countries without mother tongue are mostly immigrant countries, such as the United States, Canada, Britain, Ireland, Australia, New Zealand and other countries. Immigrants started in17th century. At that time, the British Empire was the most advanced country in the world, especially in navigation technology. They developed many areas and prospered until the beginning of19th century. They are called the empire that never sets. These countries are all members of the Commonwealth and all use English as the official language.