text: The model represents individuals as networks of interacting transcriptional regulators. Each individual expresses  genes encoding transcription factors. The product of each gene can regulate the expression level of itself and/or the other genes through cis-regulatory elements.  The interactions among genes constitute a gene network that is represented by a  ×  regulatory matrix  in the model.  The elements in matrix R represent the interaction strength.  Positive values within the matrix represent the activation of the target gene, while negative ones represent repression. Matrix elements with value 0 indicate the absence of interactions between two genes.