II. Genotype-environment interaction in the schizophrenia spectrum: qualitative observations.

Previous reports from the Finnish Adoptive Family Study of Schizophrenia have documented significant interplay between genetics (G) and family rearing (E), leading to adoptee outcomes of schizophrenia spectrum disorders. Quantitative evidence for this interplay is significantly enhanced when both high genetic liability and severe environmental dysfunction are present. However, when either genetic liability is low or the rearing environment is healthy, the adoptees appear to be resiliently protected against a pathologic outcome. Nevertheless, exceptions to this pattern do occur. Six qualitative vignettes, together with quantitative measures and categorical diagnoses from the same families, illustrate how multiple methods partially confirm one another and also suggest where further exploration of gene-environment interaction is needed.