Earlier quoted context omitted.
The problem arises that the legality of marriage was designed around traditional families. There's nothing that stops homosexuals from fulfilling their emotional, romantic, and other needs. But when you involved tax deductions because children are such an expensive commitment, it gets hairy. I do support civil unions (but not gay adoption), and I am tolerant of gays (I discuss these issues with friends who are gay),…
You do realize that if the definition of marriage had never changed, then interracial marriages would still be illegal, right?
If the definition of marriage had never changed from the 19th century, married women owning separate property wouldn't be legal.
If the definition of marriage hadn't changed from what is one in any particular time and place in the past leading up to modern marriage laws, either much broader or much narrower restrictions on consanguinity would exist.
Marriage laws change all the time, and understanding of the relationships underlying marriage on which those laws are based also change all the time. Sure, same-sex marriage is a change -- but lots of other things that we consider fairly firmly entrenched in our idea of marriages were themselves changes, some fairly recent, to pre-existing models of marriage. The whole idea that there is some single "traditional" model of marriage that has been static for an extended period of time and which is now threatened by same-sex marriage is ludicrous.