Of course this oxytocin story must involve other SNPs for the impact in your personality.
Yes, indeed... There are lots of variables (including many SNPs) contributing to disease or personality, and, of course, there is environment and the choices we make... one of the surprising outcomes of the genome project is exactly those findings (ie, complexity of SNP interaction, epigenetics). The article below is just one of the places that I've read that... This guy is talking about diseases, but I think personality traits can have the same complexity. I agree w most of what he's saying, with one big exception: he is using the complexity of genetics as an argument against investing in "Precision Medicine" which I think is ridiculous.
ps re empathy "gene" - OF COURSE there are many other factors... I guess that does need to be explicitly said.
http://www.nytimes.com/2015/01/29/opinion/moonshot-medicine-will-let-us-down.html?_r=0
"But for most common diseases, hundreds of genetic risk variants with small effects have been identified, and it is hard to develop a clear picture of who is really at risk for what. This was actually one of the major and unexpected findings of the Human Genome Project. In the 1990s and early 2000s, it was thought that a few genetic variants would be found to account for a lot of disease risk. But for widespread diseases like diabetes, heart disease and most cancers, no clear genetic story has emerged for a vast majority of cases."