The Importance of the Prenatal Environment in Behavioral Genetics: Introduction to Special Issue.

We introduce and discuss a special issue on prenatal factors in genetics research, that includes 14 papers ranging from studies on chorionicity, smoking during pregnancy, and more general prenatal risks to papers about theory, methods and measurement. There are two review papers, one focused on chorioncity and the second on pre- and perinatal ischemia-hypoxia, that help to frame the state of research in these areas with a focus on the relevance across multiple fields of study. Taken together, these papers clearly demonstrate the importance of considering prenatal environment influences on functioning in offspring across the lifespan while also underscoring the importance of using genetically informed designs as a means to clarify causality.