It doesn't need to be one or the other. Genetics can predispose somebody to be more vulnerable to certain environmental factors. They will not show any symptoms

It doesn't need to be one or the other. Genetics can predispose somebody to be more vulnerable to certain environmental factors. They will not show any symptoms unless those environmental factors are present, but there's still genetics involved. And of course there's this whole field called epigenetics that studies how the same genes can be expressed differently based on environmental factors.