A half dozen times here Ive outlined the reason that gay marriage (right or wrong) in simple to differentiate from bestiality, pedophilia and polygamy. Im unable to devote the time now to the multitude of volleys it generates each time. But in summary, it has to do with need (with some evidence of biological origins) verses a simple desire to push boundaries, frequency of that need in the population, and the destructiveness of the practice.
I apologize, but I have some important things to complete so I wont be engaging in this debate now.
There is nothing "normal" about homos. Even the wild animals know better (Except male goats. They're really filthy).