The post below on AVPR1A and fidelity alluded to the fact that this locus has been implicated in many other behavioral traits. I spent some of today digging through the literature. So check it.... AVPR1a and SLC6A4 Gene Polymorphisms Are Associated with Creative Dance PerformanceAVPR1A and OXTR polymorphisms are associated with sexual and reproductive behavioral phenotypes in humansLink Between Vasopressin Receptor AVPR1A Promoter Region Microsatellites and Measures of Social Behavior in HumansAssociation between a vasopressin receptor AVPR1A promoter region microsatellite and eating behavior measured by a self-report questionnaire (Eating Attitudes Test) in a family-based study of a nonclinical populationProvisional evidence that the arginine vasopressin 1a receptor gene is associated with musical memoryHeritability of cooperative behavior in the trust gameIndividual Differences in Allocation of Funds in the Dictator Game Associated with Length of the Arginine Vasopressin 1a Receptor (AVPR1a) RS3 Promoter-region and Correlation between RS3 Length and Hippocampal mRNA Let me quote from the last study:
Parents did not participate in online game playing. Since variation in the length of a repetitive element in the vole AVPR1a promoter region is associated with differences in social behavior we examined the relationship between RS1 and RS3 repeat length (base pairs) and allocation sums. Participants with short versions...of the AVPR1a RS3 repeat allocated significantly...fewer shekels to the 'other' than participants with long versions...Dictator Game allocations were significantly associated with the RS3 repeat...The association between the AVPR1a RS3 repeat and altruism was also confirmed using two self-report scales...RS3 long alleles were associated with higher scores on both measures. Finally, long AVPR1a RS3 repeats were associated with higher AVPR1a human postmortem hippocampal mRNA levels than short RS3 repeats...suggesting a functional molecular genetic basis for the observation that participants with the long RS3 repeats allocate more money than participants with the short repeats. This is the first investigation showing that a common human polymorphism, with antecedents in lower mammals, contributes to decision making in an economic game. The finding that the same gene contributing to social bonding in lower animals also appears to operate similarly in human behavior suggests a common evolutionary mechanism.
In other words, the molecular genetic processes which might underlay all these coarse phenotypic variations might be rather simple, the extent of the repeated genomic region has a proportional relationship to the dosage of the gene product. The product itself has a proportional relationship to particular phenotypes. Many of these behavioral traits are probably mediated by some global personality trait which affects them; e.g., impulsiveness modulating time preference and the ability to consider how selfish actions in the near term might affect one's life in the long term. Also, let me reiterate that the balance between various repeat length alleles on this locus might be governed by simple hawk-dove dynamics. Related: Also check out DRD4 and