Gay marriage does not have the same pedigree, and yet it is legal in several states.
Muslims also have polygamy but it’s is not as widespread as most people think. I knew one Arab Air Force guy who had two wives and one American muslim who had two or three wives. The rest of the men I knew only had one. Most women on that side of the world don’t play that multiple wives crap.
The muslim women claim that it is allowed if one woman is barren then the husband is allowed to get another wife so he can have children. They don’t divorce because the husbands have to give up big cash to the relatives to get married in the first place.