Specifically, our claim is that certain gene polymorphisms make certain patterns of neurotransmitter activity more likely, and that when those patterns occur in certain brain regions, they make it more likely that an individual will develop the urgency traits. As we have argued above, development of the urgency traits makes it more likely that individuals will engage in rash actions when experiencing intense emotion, which makes it more likely that individuals will engage in risky behaviors, which makes it more likely they will come to rely on such behaviors for affect management and thus experience personal harm. Thus, we are describing a series of hypothesized steps from gene to behavior, with presumably moderate effect sizes, at best, at each step. We therefore would not expect to find high levels of association between gene polymorphisms and trait scores.
