For example, if the Federal DOMA is struck down by the courts, the Federal anti-polygamy will inevitably follow.

I would like to see an actual study supporting the supposition that a polygamous family life is in some way harmful for children. I have no opinion about it being so or not, never having seen any data or observed such a situation myself. But if it is not, then I don't see why polygamy/polyandry should be disallowed by some mortalistic law. It is practiced much more widely than is generally acknowledged, and is no-one's business, unless it is harmful in some way. I can't think why having several moms or several dads in parallel should be any worse for a child than having them in serial, as is currently practiced widely. In fact I think having several would make for better support and more balanced learning, if they were basically rational folks... But I could be wrong.

As for "But who said you have more right to decide for society than Mrs. Grundy? " -- you're missing the point. I am not seeking such a right. I don't think such a right should exist, for me or anyone else, unless an issue of public health can be demonstrated.

A