The intelligence of heritability.

Abstract

The influences of heredity and environment on behaviour are sometimes quantified as a heritability ratio, which assigns a percentage of variation in test scores to variation in the genotypes of individuals. There are compelling reasons, both biological and statistical, to doubt the validity of the common practice of partitioning variance in this manner. This paper outlines the conceptual foundations and explains the weaknesses of heritability analysis, reviews evidence of heredity-environment interaction during development, and argues for an alternative research strategy to detect and understand the functions of specific genes relevant for individual differences in behaviour.

Some Conceptual Deficiencies in ‘Developmental’ Behavior Genetics

“…422-423: Walhsten. 1990.1994, and the population geneticist Lewontin as long ago as 1974 made the point that the analysis of variance is not the same as the analysis of causes. Some psychologists have not heeded these considerations and have misapplied the statistical procedures of population genetics in an attempt to explain development [the process whereby genotypes are transformed into phenotypes - Bronfenbrenner and Ceci.…”

Analysis of Variance in the Service of Interactionism

“…A similar point was made recently by a colleague in behavior genetics who chastised me, a critic of heritability analysis [Wahlsten, 1990[Wahlsten, , 1994[Wahlsten, , 1999a[Wahlsten, , 1999b, for employing the analysis of variance (ANOVA) in a recent study [Crabbe, Wahlsten and Dudek, 1999]. In reply, I argue that (a) ANOVA does not presuppose the separateness of genes and environment; (b) devotées of interactionism often employ ANOVA to examine results of factorial experiments precisely because the method can reveal the presence of interactions; and (c) all users of ANOVA must struggle with problems of interpretation, but these problems are especially severe for those who apply correlational methods to study human populations.…”

Single-Gene Influences on Brain and Behavior

“…This tension continues. Although the mathematical models of biometrics have undoubtedly become more sophisticated and are being applied to both nervous system and behavioral analysis (Rijsdijk & Boomsma 1997), fundamental disagreements abound concerning the basic formulation and assumptions of the quantitative models (Devlin et al 1997, Schonemann 1997, Wahlsten 1990, 1994, and many practitioners of quantitative genetics are being drawn to the study of single-gene effects , McClearn et al 1991. In the view of Plomin and associates (1994), "additional quantitative genetic studies are no longer needed to document the importance of genetic influence" (i.e.…”