The nature of humans requires opposite genders for humanity to survive.
Comparing homosexual unions to bans on interracial marriage is nonsense. Interracial marriages produce offspring, homosexual unions can not.
It's not nonsense in a legal sense, as I pointed out earlier.
SCOTUS struck down all prohibitions against interracial marriage in 1967. Some states did not repeal or rewrite their laws to reflect that reality until much later. Were all the marriages approved by those states after the court decision, but before the repeal/rewrite of the applicable part of their marriage laws, null and void?
Of course not. And this is but one example of something that happens across the country every single day.