diversity and organizations discussion topics

Below are two discussion questions I need to answer they do not need to be in specific paper format:

1) Scientists began identifying race as a social construct in the 1960s as noted in the opening case of Chapter 4. A social construct is a shared assumption or idea that has been created and accepted by people and society. If people are almost genetically identical and race is a social construct, why do you think people may create barriers (conscious or unconscious) between different groups of people?