Another important issue concerns specific genes accounting for the heritability of DD. A recent study using hypothetical money choices reported an association between the rate of discounting and two dopamine-related genes (Eisenberg et al. 2007), although these associations accounted for less than 5% of total variance. Given that the present findings indicate that genetic factors account for about 50% of the total phenotypic variance (at least for the real-money choice paradigm used) it is likely that many more genes are involved DD. Future studies should aid in the identification of individual genes influencing variability in decision making.
