What does a general factor of personality look like in unshared environmental variance?

A general factor of personality (GFP) was obtained solely from unshared environment, by deriving it from the intercorrelations of monozygotic twin differences. This GFP was compared with a GFP derived from correlations reflecting all three components of variance—genes, shared environment, and unshared environment. In two large samples of adult Australian twins, for the items of two questionnaires, the two approaches gave virtually identical GFPs. However, in a sample of adolescent Australian twins, the two GFPs were correlated but distinct.

► A general factor of personality was obtained from identical twin differences.
► It was compared to one derived in the usual way from individuals.
► They were virtually identical for two questionnaires in two large adult samples.
► They were correlated but distinct for adolescents.