Life ScienceSince 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....
This is basically a study which explores behavioral economic questions with the methods of behavior genetics. The interesting point is that the same tendencies on this locus correlated with the number of repeats on the gene can be found in both voles and humans, suggesting that the same switches can modulate complex behavior across many taxa. Here's a link for SNPs on this gene. Popping the gene into Haplotter does not suggest any recent selection, so this might be a case where behavioral polymorphism has persisted for a long time as different strategies maintain themselves at equilibrium. You can download a full copy of this paper here. Speaking of behavioral economics there's recently been work which elucidates the heritability of the responses to these games.
Note: I highly recommend that you check out the PDF and page down to the figures. They're pretty illustrative. Looks like the alleles work in an additive fashion, heterozygotes are in between homozygotes.
Related: Another repeat polymorphism which behavioral correlates.
