The Short Version
This claim significantly oversimplifies the science. While environmental factors are important, peer-reviewed research shows the balance between genes and environment is highly trait-specific: genetics accounts for 50–80% of variance in cognition/intelligence, and the broadest meta-analysis (14.5 million twin pairs) found only a roughly 51/49 split that includes measurement error. Modern behavioral genetics emphasizes gene-environment interplay, not the dominance of either factor. The blanket claim of environmental superiority is not supported by the weight of evidence.