Figure 1. Path diagram of the full linear moderator model.

Note. A, C, and E represent genetic, shared environmental, and non-shared environmental influences, respectively. Interactions with the moderator (i.e., M; the child’s biological sex) are added to these genetic and environmental influences, and are estimated separately for each component of variance (i.e., β_xM, β_YM, and β_ZM for a, c, and e paths, respectively). For ease of presentation, the co-twin variables and paths are omitted here, though they are estimated in the model.