The aim of the study was to evaluate whether thought disorders are stable, trait-like features specific to subjects who have a genetic liability to schizophrenia or a psychiatric disorder. The thought disorders of adoptees genetically at high risk (HR) or low risk (LR) for schizophrenia from the Finnish adoptive family study of schizophrenia were evaluated twice at a mean interval of 11 years, using the sum of the Thought Disorder Index (TDI) scores on the Rorschach (TD_R). At the initial assessment, the mean TD_R scores of women were significantly higher than those of men, while no association between genetic risk and psychiatric status or their interactions with the TD_R scores at baseline were found. The main finding was that the initial TD_R scores statistically significantly predicted the TD_R scores at follow-up, thus indicating the stability of thought disorder over time. However, neither genetic or psychiatric status nor gender or any interaction between these variables associated with TD_R at follow-up.