ABSTRACT In this article, we address a number of issues surrounding biological models of personality traits. Most traditional and many contemporary biological models of personality traits assume that biological systems underlying personality traits are causal and immutable. In contrast, sociogenomic biology, which we introduce to readers in this article, directly contradicts the widely held assumption that something that is biological, heritable, or temperamental, is unchangeable. We provide examples of how seemingly unchanging biological systems, such as DNA, are both dependent on environments for elicitation and can be modified by environmental changes. Finally, we synthesize sociogenomic biology with personality psychology in a model of personality traits that integrates this more modern perspective on biology, physiology, and environment that we term sociogenomic personality psychology. We end the article with a discussion of the future directions of sociogenomic personality psychology.