Nah, I'd say their liberal school teachers are behind it, as is the case here in Canada. They try to "educate" the social conservative right out of you.
I believe that's a side effect of education in general.
Mostly it's a side effect of living on a college campus where social liberalism is the norm, although you can get the occasional professor with some kind of axe to grind about something. At least in my experience, it's not so much the class material that drives social liberalism on campus but more the school newspaper, student organizations, residential housing staff, tolerance of underage drinking and drug use, etc.
I was never preached to in elementary or high school either, though again, I have had a couple college profs with axes to grind.
