Also as we have seen, heritability changes during ontogeny as the relevant sources of variance change. Heritability does not imply a lack of plasticity. Heritability concerns shared variance, plasticity concerns mean differences. Variance can be shared even when means are moving up or down in response to uniform changes in the environment. Substantial heritability within groups does not imply that between group differences are heritable.
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.