Even this lowly Wikipedia article
goes right over nyuk's and txtebow's head...
Particularly contentious in the ongoing debate has been the definition of both the concept "race" and the concept "intelligence", and especially whether they can in fact be objectively defined and operationalized. While several environmental factors have been shown to affect group differences in intelligence, it has not been demonstrated that they can explain the entire disparity. But on the other hand, no genetic factor has been conclusively shown to have a causal relation with group difference in intelligence test scores.
Those two skip right over the above.