Individual differences in executive functions are largely genetic. A twin study examined three executive functions—response inhibition, working memory updating, and task shifting—measured as latent variables. Results showed that these functions are correlated due to a highly heritable (99%) common factor beyond general intelligence or perceptual speed, and separable due to additional genetic influences unique to each function. This combination makes executive functions among the most heritable psychological traits. Genetic approaches can help uncover biological underpinnings of executive functions and highlight the need to examine multiple types to distinguish genetic influences. Executive functions are complex, involving multiple related but separable abilities. Recent research suggests they are better characterized as a collection of related but separable abilities, referred to as "unity and diversity." Three key executive functions are response inhibition, working memory updating, and task shifting. Other functions like dual-tasking and resisting proactive interference have also been studied, but these three dominate recent research. The task impurity problem complicates interpreting studies based on single complex executive function tasks, as performance may reflect nonexecutive variance. Using latent variables as dependent measures helps isolate the target executive function from nonexecutive components. This approach showed that the three executive functions were moderately correlated but separable at the latent variable level. Neuroimaging studies also support the unity and diversity of executive functions in terms of brain localization. For example, common frontal and parietal areas are activated by all three functions, while frontal and/or posterior areas are unique to updating and shifting. The findings have methodological and theoretical implications for psychological research. Treating executive control as a multicomponent construct allows for increased specificity about its role in various cognitive, neuropsychological, and clinical constructs. For example, three complex neuropsychological and cognitive measures were found to be differentially related to the three executive functions among young adults. In the clinical domain, considering the multiple components of executive functions has led to better specification of executive deficits in various disorders. For example, children with ADHD showed inhibiting deficits, while those with reading disorders showed verbal working memory deficits. The study used twin designs to estimate the extent to which interindividual variation in executive functions is influenced by genetic and environmental factors. Additive genetic influences include the effects of many genes, while shared environmental influences contribute to similarity between twins. Nonshared environmental influences make twins' performances uncorrelated. The ACE model was used to decompose variance in executive functions into genetic and environmental components. Results indicated that executive functions are largely heritable, with genetic influences operating at both general and specific levels. This suggests that executive functions are among the most heritable psychological traits. The study found that individual differences in executive functions are largely genetic, with genetic influences operating at both general and specific levels. This highlights the potential of genetic approaches for uncovering the biological underpinnings of executive functions and the need to examine multiple types of executive functions to distinguish different levels of genetic influences.Individual differences in executive functions are largely genetic. A twin study examined three executive functions—response inhibition, working memory updating, and task shifting—measured as latent variables. Results showed that these functions are correlated due to a highly heritable (99%) common factor beyond general intelligence or perceptual speed, and separable due to additional genetic influences unique to each function. This combination makes executive functions among the most heritable psychological traits. Genetic approaches can help uncover biological underpinnings of executive functions and highlight the need to examine multiple types to distinguish genetic influences. Executive functions are complex, involving multiple related but separable abilities. Recent research suggests they are better characterized as a collection of related but separable abilities, referred to as "unity and diversity." Three key executive functions are response inhibition, working memory updating, and task shifting. Other functions like dual-tasking and resisting proactive interference have also been studied, but these three dominate recent research. The task impurity problem complicates interpreting studies based on single complex executive function tasks, as performance may reflect nonexecutive variance. Using latent variables as dependent measures helps isolate the target executive function from nonexecutive components. This approach showed that the three executive functions were moderately correlated but separable at the latent variable level. Neuroimaging studies also support the unity and diversity of executive functions in terms of brain localization. For example, common frontal and parietal areas are activated by all three functions, while frontal and/or posterior areas are unique to updating and shifting. The findings have methodological and theoretical implications for psychological research. Treating executive control as a multicomponent construct allows for increased specificity about its role in various cognitive, neuropsychological, and clinical constructs. For example, three complex neuropsychological and cognitive measures were found to be differentially related to the three executive functions among young adults. In the clinical domain, considering the multiple components of executive functions has led to better specification of executive deficits in various disorders. For example, children with ADHD showed inhibiting deficits, while those with reading disorders showed verbal working memory deficits. The study used twin designs to estimate the extent to which interindividual variation in executive functions is influenced by genetic and environmental factors. Additive genetic influences include the effects of many genes, while shared environmental influences contribute to similarity between twins. Nonshared environmental influences make twins' performances uncorrelated. The ACE model was used to decompose variance in executive functions into genetic and environmental components. Results indicated that executive functions are largely heritable, with genetic influences operating at both general and specific levels. This suggests that executive functions are among the most heritable psychological traits. The study found that individual differences in executive functions are largely genetic, with genetic influences operating at both general and specific levels. This highlights the potential of genetic approaches for uncovering the biological underpinnings of executive functions and the need to examine multiple types of executive functions to distinguish different levels of genetic influences.