Give one example of a society where women make most of the wealth and men have the main role in childcare? You won't find one because it isn't natural in the human species.
Problems occur when society tries to medal with the natural order of things.
That is one of the most unreal things I've read in a while.
People confuse the "natural order of things" and "my preferred order of things" all the time. Once a social species achieves the ability to do what it wants (as soon as things like recreation become common; there's enough communal safety and time) the society is no longer a slave to natural processes, and a society that uses nature or tradition to excuse modern dumb-ass behavior and thinking isn't really a society with a defensible position. I'm looking at you, middle-eastern cultures.
I was in jury duty once over a rape case. The rapist felt it was his right to rape anyone anywhere at any time because that's what cavemen did. We don't know how "cavemen" behaved sexually, for one thing. We don't even know what human sleep patterns were like 200 years ago*, so forget prehistoric humans and their gender roles.
The practices and beliefs of the past carried forth to today because "it's natural," or because of tradition, shows a complete lack of understanding in the progress made between the past and the present.
* there is evidence that all across the world, sleep patterns were very different just 2-3 centuries ago. Naps during the day were common enough that some businesses closed for 2-3 hours after lunch, and stayed open later. Also, there is evidence that people has "second sleeps" where they woke up after a few hours of sleep, for 1-2 hours, around midnight, then went back to sleep in early morning. There's evidence of that, but no proof. Folks just wrote about their days as if it were common knowledge, and they never seem to go into detail about it. Thus, we, just 200-300 years later, have very little idea how people slept, woke, and went their lives on a day to day basis.
So, when talking about human behavior, sexual orientation, or gender roles, saying that something is the natural order of things means that it's really just what you believe in, and you should just say that, instead.