Stick to the fundamental question: Do you support gay marriage? Is your belief moral, social or practical? Would you feel the same way if there were absolutely no religious influence on the matter pro or con?
Regardless of your belief, does every adult have a fundimental right to marry anyone of his or her choosing, regardless of gender?
If you throw out religious influence then the matter becomes a social question. Either way I do not support it. At the end of the day, It's all about money and who gets it when somebody dies: your family or somebody you dated. If we take out all the sensationalism, all motives are money based; insurance, estate, etc. With the exception of children. Tricky one. We all want to leave a legacy. I let you all do the rest.
Someone brought up the topic of non-humans but better yet someone brought up comming up with another term. I agree here, marriage is a man+woman thing.