 However, an analysis of IQ data carried out by the National Longitudinal Surveys on a survey database of American "baby boomers" (NLSY79 data), the natural blonde women in this population category (excluding African American and Hispanic persons) have a slightly higher mean IQ than brunettes, black and red haired women.On the other hand, a blonde woman is often perceived as making little use of intelligence and as a "woman who relies on her looks rather than on intelligence.