Well, since the primary argument against gay marriage is that marriage is for having children, I would think that the question of adoption would be central.
If that's the primary argument, then it is a sure loser. I think even the uneducated could see the fallacy in that line of thinking. Should women unable to procreate be banned from marriage? Or men for that matter? Should couples who fail to procreate no longer be considered married? Seems to me the two issues are NOT one and the same and those who oppose gay marriage have more reason than that for doing so. Not that I understand their reasoning.