Souds like you didn't understand the article:same sex marriage threatens the Institution of Marriage,because it changes the definition of marriage.If same sex couples can marry,why not legalize incest? There are no logical or scientific reasons to prohibit it.
...same sex marriage threatens the Institution of Marriage,because it changes the definition of marriage. On the contrary, the objection I've been seeing here is that it extends traditional marriage to gays. A 'civil union', which many support as an alternative but which is available to heterosexual couples as well, redefines 'marriage' much more thouroughly - redefines it away, in fact.