Abstract
Historically, undergraduate genetics courses have disproportionately focused on the impact of genes on phenotypes, rather than multifactorial concepts which consider how a combination of genes, the environment, and gene-by-environment interactions impacts traits. Updating the curriculum to include multifactorial concepts is important to align course materials to current understanding of genetics, and potentially reduce deterministic thinking, which is the belief that traits are solely controlled by genes. Currently there are few resources to help undergraduate biology instructors incorporate multifactorial concepts into their genetics courses, so we designed this lesson that centers on familiar, real-world examples. During this lesson, students learn how to distinguish between genetic and environmental sources of variation, and examine and interpret examples of how phenotypic variation can result from a combination of gene and environmental variation and interactions. This lesson, which is designed for both in-person and online classrooms, engages students in small group and large group discussion, figure interpretation, and provides questions that can be used for both formative and summative assessments. Results from assessment questions suggest that students found working through models depicting the interactions between genotypes and environments beneficial for their understanding of these complex topics.