The conceptual relationship between genes and social behavior has shifted significantly during the past 20 years. As genes have come to be understood as concrete DNA sequences, rather than abstractions inferred from inheritance, it has become increasingly clear that social factors can play a significant role in regulating the activity of human genes. DNA encodes the potential for cellular behavior, but that potential is only realized if the gene is expressed - if its DNA is transcribed into RNA and translated into protein (Figure 1). Proteins shape the structure of a cell, and endow its characteristic behaviors such as movement, metabolism, and biochemical response to external stimuli (e.g., neurotransmission). Absent their transcription, DNA genes have no effect on health or behavioral phenotypes. With the advent of a sequenced human genome and the emergence of DNA microarray technologies, scientists can now survey the expression of all human genes simultaneously and map the specific subset of genes that are active in a given cell at a given point in time. One surprising finding from the field of “functional genomics” is that the
