%A Wim E. Crusio %J Behavioral and Brain Sciences %T No evolution without genetic variation %X Dr. Thornhill's target article presents us with a number of hypotheses concerning rules regulating inbreeding in man. It is argued that the goal of such rules is not primarily the avoidance of close-kin inbreeding, because 'selection for the avoidance of close-kin mating has apparently resulted in a psychological mechanism which promotes voluntary incest avoidance'. %N 2 %P 267 %V 14 %D 1991 %L cogprints167