Other risk factors that contribute to the likelihood of sex crimes include biological, physiological and psychological factors Fantasy of having a vagina mental disorders especially paranoia and psychosis ; violent history, arrests, poor academic performance,  substance abusefinancial gain,   unemployment, and watching pornography. However, because of a reliance on retrospective recall, as well as response bias and Fantasy of having a vaginathere is an inherent difficulty in measuring the frequency of types of fantasies. The fantasy of teeth in the vagina must be carefully distinguished from a woman's vaginismus an involuntary spasm of the muscles surrounding the vagina that closes the vaginafrom the fantasy of a penis with teeth, from fear of incorporation linked to mourning, and from any nonoccidental anthropological data. For instance, younger men have been found to endorse more fantasies with multiple partners, a trend which declines with age, whilst homosexual fantasies increase slightly. In the case of films, the term may describe a part of the film, such as a fantasy scene or sequence. Sadistic themes are consistently present in the sexual fantasies of offenders across various types of sexual crimes and varying risk factors.