Is there only one set of genes for different abilities? A reanalysis of the National Merit Scholarship Qualifying Test (NMSQT) data.

Using the genetical analysis of covariance structure it is shown that the single factor model of Plomin and DeFries [(1979). Behav. Genet. 9:505-517J fails as a description of the structure of genetic covariation between the subtests of the National Merit Scholarship Qualifying Test. A genetic group factor which loads on Vocabulary, Social Studies, and English greatly improves the fit of the model. There is also a large portion of genetic variance specific to Mathematics and it is argued that the genetic variance for different abilities is far from homogeneous in its origin. The data suggest that a single dimension of mate selection or cultural inheritance accounts for a significant part of the phenotypic covariance between measures.