Genetics can be argued.
Quote:
"But if you choose to fight the evidence, here's what you're up against. Among white Americans, the average IQ, as of a decade or so ago, was 103. Among Asian-Americans, it was 106. Among Jewish Americans, it was 113. Among Latino Americans, it was 89. Among African-Americans, it was 85. Around the world, studies find the same general pattern: whites 100, East Asians 106, sub-Sarahan Africans 70. One IQ table shows 113 in Hong Kong, 110 in Japan, and 100 in Britain. White populations in Australia, Canada, Europe, New Zealand, South Africa, and the United States score closer to one another than to the worldwide black average. It's been that way for at least a century."
"I thought head measurement had been discredited as Eurocentric pseudoscience. I was wrong. In fact, it's been bolstered by MRI. On average, Asian-American kids have bigger brains than white American kids, who in turn have bigger brains than black American kids. This is true even though the order of body size and weight runs in the other direction. The pattern holds true throughout the world and persists at death, as measured by brain weight."
Link
http://www.slate.com/id/2178122/entry/2178123/