CDP (Dick et al., 2009). However, the data suggested a crossover effect for all CHRM2 SNPs with significant interaction effects: The genotype associated with the highest levels of externalizing behavior at the low end of parental monitoring was associated with the lowest levels of externalizing behavior at the extreme high end of parental monitoring. Although the overall test of interaction was not significant in the TRAILS sample, the markers with suggestive interaction effects also showed crossover effects.
