Income is probably the single most useful indicator, so someone like BRTD isn't all that unusual. However, with someone age 20 you sometimes look at their income, sometimes family income (my income might by 5K, but my parents are in the top tax bracket).
well my parents are in the $50-75k bracket that voted 56% for Bush, although I know for sure my mom voted for Kerry, don't know about my dad.
Not an issue for me though, once I get out of college and get my CIS degree I could probably land a job making $60-70k a year, that wouldn't change my voting though.
Of course my Protestant denomination probably voted for Kerry, even if only marginally (at least in my state), my ethnicity probably voted for Kerry (if you go beyond "white", Scandinavians in the upper Midwest tend to be Democrats) and my city voted 54% for Kerry.