Government doesn't endow people with the ability to procreate the species. The Creator takes care of that. Like all unalienable rights, those associated with the natural family exist in consequence of this endowment. A couple that cannot, by nature, procreate has no claim to those rights. Nor can government grant them a semblance of it without impairing the claims of one or both of the parents biologically implicated in the physical conception of the child. The DOMA simply makes more explicit the government's obligation to secure the Creator-endowed unalienable rights of the natural family. This obligation precludes government from fabricating other rights that impair them. In this respect, granting homosexuals the right to marry is like granting plantation owners the right to own slaves.