From Josh Divine at LifeSiteNews:
[T]here are reasoned, legal arguments against SSM. In order to understand them, one must understand the state’s interest in institutionalized marriage, which is the creation and maintenance of the most stable known family unit. While I could reasonably meet the basic needs of my daughter by myself, the best situation she could ever grow up in is one that includes both her mother and me. After all, there are more differences between men and women than physiology, and I could never succeed in teaching my daughter to become a woman without the aid of a woman.
In conversation, I have asked people dozens of times how a government could justify denying siblings the right to marry if we simply say anybody who “loves” somebody else can marry him or her. I have never received an actual attempt at a response. That’s because basing marriage on romantic attraction opens this door. It is the case that some siblings are romantically attracted to one another. It is also the case that there are numerous situations where groups of more than two people are romantically attracted to each other. The redefining of marriage on romantic attraction reduces other restraints on marriage to arbitrary tradition, tradition that will likely fade in the future with further acceptance of SSM.