The aim of this study was to find potential signs of genetic vulnerability to schizophrenia. The differences between adoptees at high genetic risk for schizophrenia (their biological mother had a schizophrenia spectrum disorder) and control adoptees of non-schizophrenia spectrum biological mothers were assessed. The comparisons between these groups were based on the Minnesota Multiphasic Personality Inventory (MMPI) test's subscale scores adjusted by gender, age at MMPI assessment, age at placement into the adoptive family and social class. The subjects were a subsamples of a total of 182 tested adoptees and 136 mentally healthy adoptees in the Finnish Adoptive Family Study. The high-risk group was found to be distinguishable from the low-risk group based on deviant scores on the Hostility, Hypomania and Lie scales. These scales may measure genetic vulnerability and also possibly be indicative of psychometric deviance predicting future onset of schizophrenia.