Vocabulary size is highly heritable. Males and females differ on average in vocabulary. Cannot conclude that the male-female difference is genetic. Heritability does not imply genetic determination because genes may well be correlated with the environments and experiences that produce differential development. Different genes may be the occasion for different treatment in which genes are the distal cause of differences but environments are the proximate cause.
Psychoactive variable can be environmental even though genes account for the variance.
Consider a society in which opportunity is rtace dependent and phenotypes depend on opportunity. In this society genetic variance would be enhanced by the differences in opportunity between the races, Consider also the case of early and late maturing males. Take case of Ressler's mice. Strain differences accounted for the major portion of the variance but we know that strains elicit different degrees of nurturing. There is a gene-environment correlation here that partly accounts for the portion of the weight differences attributable to strains, i.e., the identical genotypes.