http://www.foxnews.com/scitech/2010/10/28/researchers-liberal-gene-genetics-politics/
It is a combination of many factors. There has been a lot of research on left brain/ right brain activity. I do believe this is one factor. But also other factors can be family background, social group, and even personality factors. Personal interest and lifelong study of politics can influence as well. Biological factors do influence behavior, but a specific gene for liberalism: I would have to read the actual study to see about that.
I believe that there is a certain spin ( Bill OReily) when people quote scientific studies. Also the studies can be flawed. And therefore not reliable or truthfull.
Okay seriously, that is biggest bunch of b.s. I've read in a long time. You cannot blame a persons ideology on genetics.