There is some support for Cloninger’s ideas from the field of molecular psychiatry and the mapping of candidate genes for dimensions of human personality traits. In three studies (Benjamin et al 1996; Ebstein et al 1996; Lesch et al 1996), the dimension of novelty seeking (which includes exploratory excitability, impulsiveness, extravagance, and disorderliness) was linked to the seven-repeat allele (or long form) of the 16-amino-acid polymorphism of the D4 dopamine receptor gene (DRD4), and in another study harm avoidance was associated with the short form of a functional polymorphism (44-base-pair insertion or deletion) in the serotonin-transporter-linked promoter region (5-HTTLPR). These results provided empirical support for Cloninger’s claim that the temperament dimensions of novelty seeking and harm avoidance have an identifiable genetic basis.
