We can define natural as something that "comes by itself". Seed grows naturally. No effort is needed by man, weather or something else.
If by nature man is polygynyous then logically it follows than 2 wives are better than one. Such conclusion should come naturally since it comes from instinct. And instinct can never be hidden, only "pushed out of consciousness". It takes brain washing to "push out" instinct.
Is man by nature polygynyous? Yes, it is. Evidence is everywhere if you dare to look. Evolutionary psihology (what is path to most succesful children?). Since our Creator is mega giga ultra polygynous (how much believers/wives He has?) then it follows than mankind has inherited this part of his nature, just in smaller measure.
So why some men claim that one wife is enough? They are lying, thats way. What will other people say? If I say truth to girl she will leave me, tell everyone and I will forever be alone. Best course is to hide. Yet, we all know that when a man has a chance to have two girls without negative consequences he will take it.
By the way, women also know at instictive level that men are polygynous. But current societal situation allows women opportunity to reduce competition.
I show you path to 12 wives and answers are mostly "it is fantasy". Instinctive answer would be "fantastic". I have cited Isaiah 4:1 where Lord promises 7 wives. Is 5 more "a bridge to far"? I believe that nobody has answered using pure instinct, nor I can detect checking my logic.
Compare this two posts:
@The Revolting Man post is holding up. His caption is "proper" in today's society. It offers excuse of "forgetting" girlfriend. Like it is believable that man would forget his girlfriend literally sitting on him.
@MeganC answer is pure gold. It comes from pure instinct. It's entirely natural having two girlfriends.
Here is another post using instinct:
I would say 12 bras are >>>>>>>>>>> than 1. And yes, there is path to 12. Why is getting all you to admit this like chiselling stone with wood?