> The problem arises that the legality of marriage was designed around traditional families.
The current legalities around marriage are mostly based directly on the idea that a marriage is a special bilateral promise of mutual support, and not much on other features of "traditional" families.
They've also changed a lot over the two centuries to remove most of the vestigious of the older model of the wife being legally subordinate to the husband. Marriage legalities, and the underlying model of the relationship in marriage on which they are based, aren't the product of some long-static "traditional" model that had been undisturbed for an extended period of time before the same-sex marriage debate.
> There's nothing that stops homosexuals from fulfilling their emotional, romantic, and other needs.
Actually, not having access to the legal rights involved in marriage does prevent that.
> But when you involved tax deductions because children are such an expensive commitment, it gets hairy.
The tax deductions on that premise require you to have children that you are responsible, they aren't an automatic consequence of marriage. So I don't see how they are relevant. The situation in which marriage has tax benefits is if, as part of a couple's arrangement of mutual support, one focuses more on work outside of the house (which is taxable) supported by the other taking on a heavier load of the domestic duties, since married couples pay lower taxes than two individuals when there is a significant disparity of income.
So I'm not sure how your statement above has anything to do with marriage. It seems to have something to do with not wanting people to get tax deductions or credits that come with raising children without actually raising children, which is sensible but completely irrelevant.
> I do support civil unions
Given your statement above about the "legality of marriage" and that "civil unions" as opposed to "domestic partnership" is usually the term given for providing the legalities of marriage under a different name, why?
> (but not gay adoption)
Why? Is it that you prefer children to have less chance of having permanent families and spend more time in foster homes? Or just because you dislike homosexuals?
> and I am tolerant of gays (I discuss these issues with friends who are gay)
And I'm sure they appreciate your magnanimity in deigning to discuss with them the reasons why you think they should receive unequal treatment under the law.
> but to change the very definition of marriage goes too far - and ends up confusing everyone.
"The very definition of marriage" has been pretty much continuously changing throughout all of history. Its not all that confusing, and, to the extent it is, your desire to avoid dealing with the confusion of changing social institutions isn't a reason other people ought to suffer discrimination.