Here's the most novel reason I've ever heard.
A former solicitor-general (under George W.Bush) argued against same sex marriage in a case being heard in California. As he explained it, same sex couples don't need marriage because they can't accidentally get pregnant.
Now, if you think there is a logic link missing there, I'm with you!
Check out the full story at
http://www.salon.com/2013/01/28/gay_marriage_opponents_use_knocked_up_defense_in_supreme_court_case/?/2013/01/28/gay_marriage_opponents_use_knocked_up_defense_in_supreme_court_case/?utm_source=twitterfeed&utm_medium=twitter