Most of the people in Latin America can trace their ancestry back to the following THREE groups.

Native American

European

Australian

Asian

American

African

European, African, Native American

Explanation:

This is because of the history of the region. The Europeans during their exploration (remember Christopher Columbus?) discovered this new continent and settled down. Farming was their main economic activity at the time. Because they needed cheap labor, they engaged in slavery by importing slaves from Africa to work on the farms. The interaction between the two races is attributed to the current race in South America. Native Americans due to their close proximity have also interacted with the races in these regions.