>>Either the government can regulate marriage or it can't.
Your rights end where mine begin.The right of blood relations to marry end when the rights of the unrealized issue of their union come into play.
By the way, a great number of States OK the marriage of blood relatives as long as there is an agreement, or no possibility, of any issue.
Well which is it now? Blood relations should be barred from marrying or is it okay because some states permit it?
And as to "The right of blood relations to marry end when the rights of the unrealized issue of their union come into play." Some consider bringing up children in a homosexual household causing detrimental harm to kids. This is why some people are for prohibiting sanctioning same-sex marriages and homosexual adoptions.
We can quibble over whether harm is caused in such households but you set yourself up for that one. You DO admit that the government gets a say in "non-traditional" households.
Again, society protecting the future.