I argue with people about this all the time. I'm completely against the idea and I have a couple of reasons to back this up. This is NOT ment to offend anyone, and if you think otherwise please feel free to argue and ill do my best to show you the other side. Who knows, you might even change mine.
Ok so listen up, your 12 and have 2 dads, it's your first day of high school and your dads walk up with you. Everything is fine it's going well your making friends, until they see your dads. They'll consistently pick on this kid through high school: believe me, I've seen it happened to a boy in my class through high school, he was beaten up and teased for having two dads.
Now another reason, the whole point of a marriage is to unite two people of opposite sex. OPPOSITE not SAME.
Another reason, it's a pain in the but.
Last reason, once gays get there ways do you really think they'll just stop at that? Then they'll want same sex pregnancy to be legalised.
Good luck to you all, keep in mind I am a good arguer, no swearing or cussing aloud to prove your point please

that's the only rule.