There appears to be suf-ficient evidence thatparaphilia, or the tendency to substitute repro-ductively non-significant sexual goals for a mate of the opposite sex, is sufficiently widespread in human populations, involves sufficiently lowered fertility and is under enough genetic control to affect the distribution of genotypes in such human populations as have been well studied. Psychoanalytic theory suggests that the most probable mode of operation of the genetic determinants is on the rates of development of neuro-psychological mechanisms involved in identification processes and other aspects of object relationship in infancy. As such, they may have pleiotropic effects of importance. A consideration of fetichism suggests that certain aspects of sexual selection in man may involve mechanisms neutralizing castration fear, and so may ultimately influence such maturation rates. The type of display involved, which seems different from ordinary epigamic display in the lower animals, is designated cryptandric.