Genetic and Environmental Influences on Schizotypy: A Community-Based Twin Study

This study investigated the factor structure and etiol-ogy of four self-report schizotypy questionnaires dur-ing young adulthood (age 18-27) in 98 monozygotic and 59 same-sex dizygotic twin pairs from the commu-nity. A single phenotypic factor was identified that was primarily associated with Perceptual Aberration, Magical Ideation, and the Rust Inventory of Schizotypal Cognitions scales, and less so with Social Anhedonia. Univariate etiologic models suggested that in addition to nonshared environmental influences, Perceptual Aberration and Social Anhedonia were sig-nificantly influenced by either genes or shared family environment, whereas Magical Ideation and the Rust Inventory were influenced by shared family environ-ment, but not genes. Multivariate twin analyses detected a common schizotypy factor, primarily defined by Perceptual Aberration, Magical Ideation, and the Rust Inventory scales, that was influenced by genes or shared environment as well as nonshared environment. Contrary to expectations, these results suggest that, at least in community-based samples, these "positive " schizotypy questionnaires are not strongly genetically influenced