1) Language is closely intertwined with ethnic identity and group membership. Members of ethnic groups often learn the linguistic varieties associated with that group.
2) In the United States, differences exist between the English spoken by white and black Americans, and ethnicity can often be identified based on language alone. However, these linguistic differences result from learned behavior within communities rather than innate qualities.
3) The situation in former Yugoslavia demonstrates how ethnic identities and linguistic varieties can change over time and in response to political situations. Serbo-Croatian was once considered a single language but is now considered separate Serbian and Croatian languages.