This is how it applies. Let's take natural phenomena which have a potential to be disastrous: earthquakes, tsunamis, hurricanes, viruses etc. Imagine mainstream economists, sociologists, lawyers, physicians who try to find a way to make the phenomena less disastrous or eliminate effects of them. They will lounch massive research programs and come up with the whole spectrum of solutions in all sorts of settings and situations: dams, embankments, high building regulations, deep basement regulations, vaccinations, isolation wards, special relief agencies, price controls, prohibitions, special law enforcement, federal funding etc.
An apriorist will tell that all these solutions are misguided (yes, unscientific) because of one fundamental reason: one huge factor is not taken into mainstream equations which is state intervention/aggression. We can only know how much disastrous natural phenomena are if we know how much disaster is caused by state intervention/aggression.
Let's take Katrina. How much damage was caused by the hurricane and how much by state intervention/aggression such as taxes, subsidies, inflation, tarrifs, regulations, price control, prohibitions, welfare, law enforcement, state education? How many building were built there by cheap credit; how many people lived there supported by welfare, how many miles of subsidized roads were build there, why state education did not teach people not to live in floodplains, why the price mechanism of heavily regulated insurance companies was blocked so it would be too expensive to live there? You can only know if you eliminate state intervention/aggression. You can't eliminate hurricanes.
Let's take Spanish flu. Was it a virus or massive troop movements after the war which killed 20-50 million people? You can only know if you eliminate masive troop movements. You cant eliminate a virus.
And now let's take bad genes. How do you know how much damage in human life is caused by a natural phenomenon, a gene, and how much by human aggression?. You can only know if you eliminate aggression. You cant eliminate a gene.