Correlations for genetic and environmental effects between ages (see Table 3) were high for genetic influences in both males and females and for shared environmental effects in males. However, non-shared environmental effects for both males and females and shared environmental effects in females were not as highly correlated between ages. These results suggest that in males, specific genetic and shared environmental influences on substances used remains largely constant across ages, while the non-shared environmental influences are largely age specific. In females, however, only the genetic components remain the same across ages, while both shared and non-shared environmental factors seem to be due to age-specific influences.
