ABSTRACT
This chapter focuses on genetics and the environment as a prelude to examining the reasons for differences among siblings within a family. It examines: human beings are organisms with a genetic infrastructure; children are born with their own temperament, predispositions, and potential abilities, and these participate in determining child outcome. The chapter presents the research on twins and adoption, sometimes referred to as “natural experiments” in behavior genetics. It explores the problems inherent to the assessment of genetic similarity between parents and children. Most personality characteristics can be explained by genes as well as by “correlations” between genetic and environmental factors. These correlations form the cornerstone of the dynamics between genetics and environment: they help explain how genes and environment work together to produce outcomes. One important contribution of behavior genetics is that it emphasizes differences within families, while developmentalists generally compare children between families.
