I don't agree with your train of thought.

You say the essential difference between straight and gay marriage is the mixing of genes. But as CRC has pointed out, gays can mix their genes via IVF the same way that straights can. The state doesn't give tax preferences based on how the dependent child entered the family.

In the tax code, the benefits of marriage (joint filing, claiming exemptions, inheritance, stepped-up basis on home sale, etc., etc., etc.) don't have anything to do with children. They're a benefit of marriage. The tax code benefits of children are explicitly different.

I really don't think that continuing to restate your strongly held opinion is helping your case. Society has moved on. We don't issue marriage licenses with the expectation that blacks won't marry whites, or that husbands will have 5 wives, or that brides will be less than 16 years old any more, either. Your citing expectations of children does not change the fact that the law and the rules do not impose that requirement, and the tax code specifically addresses children under different deductions, exemptions, etc., than for marriage itself.

The equality argument is based on the equality of people. Not that "breeders" are better than "non-breeders". If legally married people have certain benefits and responsibilities, then it doesn't matter if that legal marriage is religious or secular, or between people who are fertile or those that aren't, or ... Marriage = Marriage because people must be treated equally under the law.

FWIW.

Cheers,
Scott.