I was making the statement under the assumption that OP was talking about the US, considering he's from Texas. Lol. I also misspoke, the concept is just flat out religious-based.
Well, if the OP wanted the thread to be addressed only for Americans, he should have said so...
Anyway, it's not necessarily religious based:
"The historical record offers contradictory evidence on the development and extent of monogamy as a social practice. Laura Betzig argues that in the six large, highly stratified early states, commoners were generally monogamous but that elites practiced de facto polygyny. Those states included Mesopotamia, Egypt, Aztec Mexico, Inca Peru, India and China.
Both the Babylonian and Assyrian families were monogamous in principle but not entirely so in practice since polygyny was frequently practiced by the rulers.
Although an Egyptian man was free to marry several women at a time, and some wealthy men from Old and Middle Kingdoms did have more than one wife, monogamy was the norm.
As against Betzig's contention that monogamy evolved as a result of Christian socio-economic influence in the West, monogamy appeared widespread in the ancient Middle East much earlier."
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At the end of the day, no matter how you look at it, whether in mongamy or polygamy, the institution of marriage almost always included both genders. That was the norm long before christianity. Now it's another question that practicing homosexuality was widespread in certain societies- but we're talking about marriage here.
Anyway, really, as I said few pages ago, if the majority of a particular country would vote for it, fine.