Polygamy affects more people though. All the children, who have to get along with all their half-siblings, their many squabbling moms, and one worn out dad.
Yeah, that sounds pretty bad, too.
Polyamory also includes women with multiple male partners. So not only do you have to deal with inlaws through multiple wives, but also your wives' multiple boyfriends.
Family trees will look like grapevines in a short time.
I know several polyamory people. They are not mentally oe emotionally stable.
Pinz