BGmisc: An R Package for Extended Behavior Genetics Analysis

The field of behavior genetics focuses on illuminating genetic and environmental influences on individual differences.Traditionally, twin studies have been at the forefront of this discipline. However, research has moved beyond the classical twin design to embrace more complex family structures such as children of twins (CoT), mother-daughter-aunt-niece (MDAN), and other extended family designs. These expansions allow for a deeper, more nuanced exploration of genetic and environmental influences, but it also introduces challenges, particularly in data structuring and modeling. In particular, the data structures inherent in these more complicated family designs are orders of magnitude larger than traditional designs. In the classical twin study, for example, a family will consist of a single pair of twins (i.e., two people), whereas in the MDAN design, a family consists of two mother-daughter pairs (i.e., four people). This problem quickly becomes intractable when applied to very extended family pedigrees, where a single family can be of any size. The `BGmisc` package addresses this gap by offering a comprehensive suite of functions for structuring and modeling extended family pedigree data.