How are adoption studies used to address the nature/nurture debate?

The nature/nurture debate centers on whether nature (genetics) or nurture (environment) plays the primary role in the development of personality (traits). Adoption studies are used to address this because children who are adopted share an environment with their adoptive parents, but share genetics with their biological parents. Adopted children can be studied to see whether their personality best matches their adoptive (nurture/environment), or biological (nature/genetics) parents.

How has Duverger's law shaped the American party system?

Duverger's law states that proportional representation tends to lead to the creation of multi-party systems, while elections with single-member districts favor two-party systems. Single-member districts tend to create two-party systems because in a single-member district system, in order to be elected, a politician has to win a majority of the vote. This is easier to achieve when there are only two parties competing for voters. Because America uses single-member districts, our two-party (Democrats and Republicans) system has existed since the introduction of political parties.

How did the Immigration Restriction Act of 1924 demonstrate the sentiments of the Red Scare?

The Immigration Restriction Act of 1924 limited future immigration from all countries outside of the Americas to 2% of the population of immigrants from that country living in America in 1890. The date was set at 1890 because prior to that decade, most immigration was from Northwestern Europe. After 1890, most immigration to the United States was from Southeastern Europe. The act was designed to reduce the number of immigrants for Southeastern Europe. This is connected to the Red Scare because the people that Americans feared during the Red Scare were anarchists and communists, who were believed to be primarily immigrants from Southeastern Europe.