-Dr Lidz's energetic critique
ot the Danish adoption studies of schizophrenia1 will be familiar to readers of this journal. Because Kallmann's early studies of schizophrenia seem, quite tangential to our article we only briefly address that aspect of Lidz's letter. Lidz exaggerates the degree to which Kallmann's methodology and results misled future researchers. One expert recently characterized Kallmann's twin study of schizophrenia as "basically sound."2 The same expert reviewed rigorously conducted contemporary twin studies of schizophrenia to compute a weighted average of probandwise concordances. The results, 48% for MZ twins and 17% for DZ twins, suggest high heritability, Lidz's selective review notwithstanding. We are baffled at Lidz's decision to attack our article through the relatively iron-clad fortress of schizophrenia genetics research. The substantial hereditary component in schizophrenia is surely one of the two or three bestestablished facts in psychiatry.
More relevant to the task at hand, we welcome