Further considerations for power in sibling interaction models

Abstract

Sibling interactions aim to determine whether siblings' phenotype have an impact on one another. We explore the power to detect sibling interaction term in twin models with the inclusion of singletons (only children). Furthermore, we develop the existing work on the improvement of power from the addition of unrelateds (adoptive or step-siblings). We find that singletons are considerably more powerful under cooperative (positive or imitation) than competitive (negative) interaction. Additionally, the power from URs is attenuated when common environment is part of the genetic model.