Polygamy, obviously, not to mention pedophilia, bestiality, and God know what else.
The "If it feels good, do it" crowd seems to be in control at the national level. The states are a different matter...
Doubt it.
Supreme Court jurisprudence since 1948 has been slowly abolishing the "states" as anything other than administrative divisions of FedGov, and the states seem to like that just fine.