So we agree that to an iron age farmer, plowing is almost as magic as rain dances, and a plausible evolutionary explanation why we tend to pick up the latter is that if we reject the former, we end up dead at a young age?
If so, the discussion about how rejecting norms might lead us to abstain from forming families is purely speculative. The proposition that not following norms may lead us to reject a family and kids and thus leave us to die alone when we're old is not a necessary ingredient to explaining the existence of (and our propensity to adhere to) those norms if we have independent reason to believe that not following norms will likely lead us to starve to death in a harsh winter/unusually long dry season long before that. It thus falls victim to Occam's razor. You can still speculate about it, but doing so isn't very scientific.
Perhaps it's speculative, but the larger point is kind of an inverted way of saying the same thing. If we imagine someone who is born with a severe developmental disability, or with a dysfunctional reproductive system, in the most literal sense of the term they a) can't adhere to norms b) won't make up the majority of a population. They fall out of the gene pool or make up a small proportion of it. So yes following norms is adaptive, but it follows from that, that an inability to follow norms is maladaptive. By definition culture orients us to have children, if any quality of our genetic make up, whether physical or psychological, inhibits us from having children, it's inhibiting us from following norms.
No that doesn't mean the lack of the trait is selected for, where I agree with you. But it does mean that mathematically our species are predominantly norm followers.
Sure, but if/when there is little limitation in what norms can look like (beyond those posed by other aspects of our cognitive biology), the mere fact that we tend to adhere to them does little to impose boundaries on what kind of societies we can form. That's in contradiction to what you said in your last post, namely " when we try to scale this trait to macro-systems it causes an inherent flaw in those systems".
And this is where our mental-make up becomes the critical question. Ultimately the efficacy of our macro-systems stem from our individual abilities. So it brings us back to the question - what are people like - and is their predisposition a constant. My argument is that culture is a kind of limiting factor which orients the majority of our species in a certain way. The question is what this orientation is and how it influences the movement of our systems.