, 2002). It is now widely believed that vulnerability to bad behavior is conditional and depends on genetic susceptibility (Kendler, 2001; Rutter & Silberg 2001; in Caspi et al., 2002).

This theory was tested by Caspi et al. (2001) when they attempted to predict antisocial behavior among more than 1000 male maltreated children by genotyping their polymorphism at the MAOA gene. Their findings provided epidemiological evidence that high MAOA expression moderates the effect of maltreatment and partially explained why not all victims of maltreatment grow up to retaliate by victimizing others (Caspi et al., 2001). In this case, genotype (polymorphism at the MAOA gene) is shown to moderate children's sensitivity to environmental insults (maltreatment).

Having said that there are certain characteristics where genes play a moderation role to the environment, the opposite can also be true. One of these characteristics is cognitive ability among children. It is widely accepted that...
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