FIGURE 2.

The interplay of genes and environment: the role of gene–environment interaction and correlation.

Note. A single-headed arrow from X to Y indicates that X is a cause of Y (e.g., family norms are causally related to physical activity) or that X causes increased exposure to Y (e.g., genetic factors related to exercise predisposition affect selection into exercise-promoting environments). A line intersecting a 1-headed arrow (in the form of a T) indicates that the factor modifies or modulates the relation between X and Y. Positive or negative feedback loops are indicated with an R (reinforcing) or a B (balancing).