Your question is too broad.

That is what I am telling you.

This can be eventually boiled down to nature vs nurture (this is the crux of your question), which is largely an unanswerable question.

We know that good genetics on its own does not stand to be a perfect scenario, we also know that perfect health doesn’t work either. What I am saying is it is both in unison to provide success, and not one or the other - hence the question of which provides the largest benefit is more or less is not a useful question.

Not really - we know the immune system quite well, you just can’t point to any one problem based on the question you are asking.

Almost 60-70% of medicine comes down to the immune system in some form… either too proactive (lupus, MS, Myasthenia Gravis… etc.) or not good enough (cancer, infection… etc.)

Lets simplify this greatly.

The immune system is a very complex interplay of just about everything in our lives. We have components that just are, and dynamic components which react to stimuli.

It is very unlikely for two healthy people where one gets sicker than the other to have a truly pinpointable problem, unless they have an undiagnosed biochemical/immunological problem.