The social genome: Current findings and implications for the study of human genetics

Human health and diseases are influenced by genes and environments [1]. Recent advances in measures of genetic influences have led to calls for parallel advancements in methods to measure environments [2,3]. The article by Baud et al. [4] in the January 2017 issue suggests one provocative path forward: measure the genomes of proximate individuals. "Social genetic effects" (SGEs, Baud et al. [4]) arise when an organism's phenotype is influenced by the genetic makeup of that organism's social environment. To put it another way, SGEs occur when the genotype of organism A influences the phenotype of organism B [5,6] (Fig 1). Previous SGE research focused on related individuals, especially mothers and offspring [7]. Recent work has explored SGEs in unrelated individuals, with a focus on a narrow range of phenotypes, e.g., sexual display behaviors [8] and body size [9]. The study by Baud et al. [4] suggests SGEs are more pervasive. To the extent results obtained from cage-dwelling mice generalize to free-living humans, findings suggest social genotypes are important environmental parameters.