LISREL MODELING - GENETIC AND ENVIRONMENTAL-INFLUENCES ON IQ REVISITED

This article reports a model-fitting analysis of the covariance structure of the world's IQ data as reviewed by Bouchard and McGue (1981). A model is used which includes additive and nonadditive genetic parameters, and shared and nonshared environment parameters that permit different estimates for different types of relatives. The opportunity is taken here to explicate the use of LISREL for such purposes. The results indicate that, when assortative mating is included in the model, nonadditive, as well as additive genetic variance, is important for IQ. Broad heritability is estimated to be .51. Another interesting result is that the influence of shared environment differs in a reasonable way for different types of relatives: twins > siblings > parents and their offspring > cousins. © 1990.