Multinomial logistic regression (via conditional GMM; see Wang & Bodner, 2007) was used to determine whether CHRM2 genotypes were differentially predictive of discrete patterns of externalizing behavior. Table 4 displays results from a series of nine genetically informative models in which the probability of trajectory class membership was independently regressed on the genotypes for each of the nine SNPs. Cross-tabulations of probable trajectory class membership by genotype suggested that the likelihood of displaying the normative form of development, the decreasing low externalizing trajectory, decreases with each additional copy of the minor allele; a pattern that was evidenced across all nine SNPs. Thus, carriers of the minor allele appeared to be at greater risk of developing along one of the two higher-risk externalizing trajectories. However, given the qualitative nature of these developmental classifications, multinomial logistic regression models were used to assess whether the number of minor alleles at each of the SNPs was differentially associated with the probabilities of membership for any two trajectories. As such, we found evidence that CHRM2 genotypes were significantly associated with such differences when contrasting the
