ABSTRACT

The field of behavior genetics (BG) seeks to explain the genetic and environmental factors that underlie individual differences in behavior, broadly defined (reviews in Plomin, DeFries, McClearn, & McGuffin, 2008; Rutter, 2006). Thus, BG research explores why some people are more extroverted, at greater risk for depression, and have higher blood pressure, to name a few examples. BG research is frequently presented in the classic nature versus nurture debate, where one perspective wins and one loses. This perspective treats the results of BG studies as either/or – either genetic factors explain more variability in the outcome or environmental factors are more important. Based on this approach, some researchers have made strong claims that parenting and other family-level risk factors are insignificant (Harris, 1998; Rowe, 1994) because virtually all behaviors are influenced by genetic factors and environmental factors that make siblings similar are not that influential (Turkheimer, 2000). In reaction, many psychologists have criticized the field of BG, saying that traditional BG research does not test underlying causal mechanisms (Gottlieb, 1995), includes invalid assumptions (Wahlsten, 2003), does not take into consideration developmental issues (Lerner, 1995), and is based on samples with limited generalizability (Stoolmiller, 1999). Yet the results of BG research, when properly understood, do not suggest that genetic factors are inherently more important than the environment, or that parents don’t matter. Rather, when interpreted correctly, BG studies and psychological research have concluded that both genetic and environmental factors are important and must be viewed together (reviews in Plomin et al., 2008; Rutter, 2006).