Oftentimes twin studies are conducted using data collected at a single assessment in order to estimate the degree to which genetic and environmental influences account for variation in a behavior or trait. However, it should be noted that heritability estimates are not static, and can change over time. This is especially important to consider for a behavior like conduct disorder, for which there is some evidence for differences across development (Loeber et al., 2000; Moffitt, 1993). This raises two potential questions from a genetic perspective: First, does the degree to which genetic influences account for variance in conduct disorder change across time; and second, are the genes that contribute to conduct disorder earlier in childhood/early adolescence the same as those that contribute to conduct disorder later in adolescence?
