I read a tiny bit of your link. When they say 16% of cultures are monogamous, or whatever it is, what is the sample of cultures? Is that counting a tiny African tribe as one culture, and Europe as one culture?
Our culture and most of the world's major cultures are monogamous and have been for a thousand years or more. Will you please concede the point?
Now that you put it that way, okay.
But why does that mean that the government should be involved in defining the meaning of a marriage contract?