Inborn and acquired intelligence: an old problem revisited

The variance of IQ in a population is by defi nition the sum of the partial variances of genetic and environmental variation, expressed by percentages. But the cooperation between genome and environment, resulting in the phenotype, for instance in the measured IQ, is not additive but cooperative, that means nonlinear. Therefore the fi rst of the two partial variances represents the realised part of the genetic potential which therefore is present in the phenotype; but the second term represents, as the following analysis shows, the non-realised genetic factors because of lacking environmental effi cacy, formally the product of environmental effi cacy with minus sign. This has been overlooked till now because of the loss of the “minus” sign by the quadration operation involved in the mathematical step from variation measures to variances.