Hogwash. The ultimate stated purpose of our Constitution is to "secure the Blessings of Liberty to Posterity." The natural family is the fundamental institution God designed to be the nursery of that posterity.
Four States were allowed into the Union only on the condition that they forever swear off plural marriage.
Do you want to expel Oklahoma, Arizona, Utah and Idaho from the Union on the basis of your revolutionary idea that government has no interest in the institution of marriage as the guarantor of its future survival and prosperity?
Or, do you think it's okay if particular States reinstitute polygamy?
I have a hard enough time believing states should require a license to fish in waters open to the public. I do not see room for government in my relationship with God nor in procreation.