Ethnicity can affect the surname that is chosen for a child, but it doesn't always. A child is usually given the surname of the father. The surname can provide indicators about where a family's roots may lie.
Surnames can differ depending on the region in which the family lives. In some East Asian countries, the surname is put in front of the first and middle names. Surnames were once determined by a person's social class and culture. There are some people in the United States, such as descendants of African slaves, who do not know what their ancestors' surnames are because of the history of slavery. They have the names given to their ancestors by the slaveholders.