A sample of children (n=92), derived from a representative population sample of healthy young Finns (n=2149), was studied from childhood to adulthood over 14 years to determine whether the childhood environment moderated the effect of dopamine receptor gene (DRD4) polymorphism on novelty seeking (NS). A significant interaction between the DRD4 alleles and environmental variables was observed. When the childhood-rearing environment was more hostile (emotionally distant, low tolerance of the child's normal activity, and strict discipline), the participants carrying any two- or five-repeat alleles of the DRD4 gene had a significantly greater risk of exhibiting NS scores that were above the 10th percentile on a population distribution of 2149 adult Finnish women and men. The genotype had no effects on NS when the childhood environment was more favorable. Although the results are preliminary, pending replication, they nevertheless provide important information on the long-term effects of nurture and nature on NS temperament.