>This is definitely true, but all of these genes have been vetted by millions of years of evolution, so we know they're rock solid.

Evolution does not vet for anything except population-level viability. Once upon a time, our population bottlenecked. The return of large-scale genetic diversity is normal for an animal species, especially one that has spread to practically every environment on the planet.

Also, evolution is not a prescriptive standard. Oy.