ABSTRACT Are highly heritable attitudes more or less complex than less heritable attitudes? Over 2,000 participant responses on topics varying in heritability were coded for overall integrative complexity and its 2 subcomponents (dialectical complexity and elaborative complexity). Across different heritability sets drawn from 2 separate prior twin research programs, the present results yielded a consistent pattern: Heritability was always significantly positively correlated with integrative complexity. Further analyses of the subcomponents suggested that the manner in which complexity was expressed differed by topic type: For societal topics, heritable attitudes were more likely to be expressed in dialectically complex terms, whereas for personally involving topics, heritable attitudes were more likely to be expressed in elaboratively complex terms. Most of these relationships remained significant even when controlling for measurements of attitude strength. The authors discuss the genetic roots of complex versus simple attitudes, implications for understanding attitude development more broadly, and the contribution of these results to previous work on both heritability and complexity.