What is the root cause of, say, scurvy? Some millions of years ago, our monkey ancestors lost the ability to manufacture vitamin C in their own bodies. Since then, anyone who stops eating enough vitamin C faces scurvy.

But this is not actionable, as another commenter says. We cannot yet fix our genomes to bring internal production of vitamin C back online. So we say that root cause of scurvy is lack of vitamin C in that person's diet, which can be fixed very easily now.

If/when technologies like CRISPR mature enough that playing around with genes and their expression becomes a routine thing, we might change our genomes so that vitamin C gets produced internally again, thus shifting the perceived root cause.