In the mid-1960.s, reports came from Scotland and England of a high frequency of gonosomal aberrations among male patients in maximum security hospitals (Jacobs et al., 1965; Casey et al., 1966). This led to a lively discussion. If these observations could be generalized so as to apply also to similar institutions in other countries, the question would be whether gonosomal aneuploidy had any bearing on the development of criminality and psychic diseases? In particular, the significance of a double Y condition as a predisposing factor was called in question. Unfortunately, from the outset the discussion became too categorical and oversimplified. When in subsequent studies socially well-adjusted individuals of normal intelligence were found, it was doubted whether aneuploidy had any importance at all. In a survey as recent as 1972, for example, Owen questions whether there is any connection at all between excess Y-chromosomes and behaviour disorders and mental diseases. Hook (1973), on the contrary, in a somewhat more detailed compilation, shows that there is a clear connection between the occurrence of double Y-chromosomes and individuals whom he defines as ‘mental-penal’. A common feature in all the literature, however, is that almost all writers insist on the importance of more research in this field.