EXACTLY!
And I think this can also be the counter argument for christians against the idea posed by Disgusted/Howie.
It's not that two people of the same sex are getting "married" that's the big problem, it's the projection and gross distortion of what a "family" is, or should be. I'll admit the definition of a true father has been lost for some time but I think we're still hanging on a thread to what at least a "family" should somewhat resemble.... 
Yes, but what actual harm does it do to anyone else if a gay couple gets married?
Other than some vague, subjective stuff about some moral value of "the family".
One would think that gay marriage is going to cause Ward Cleaver to go fruity and leave June , Wally and the Beaver?!
It is pretty simple to me, if you are GAY, than you are GAY, if you are straight you are straight. You can't catch GAY like some cold virus.