We'll never know because it's a taboo topic. So we'll just pretend that almost every aspect of our body has racial differences due to populations being exposed

We'll never know because it's a taboo topic. So we'll just pretend that almost every aspect of our body has racial differences due to populations being exposed to different environments/conditions and evolving to adapt, yet magically this one organ, the brain, is perfectly steady across time and location. Regardless, it's probably a "close enough" call and culture might be a larger factor. Which one can also only selectively talk about. For example, everybody knows why Asians outperform whites: performance culture and work ethic.