It should be clear; however, that there would be multiple reasons the pattern exists, ranging from the type of work most likely chosen by a specific gender or race to perceived value of an individual based upon their gender and/or race.
As an example, a male with less than a high school diploma might work as an offshore laborer, on a pipeline, or as a mechanic. A female, black or white, is less likely to work those positions leaving them at the lower end of the earning window.
This does not explain the gap between race and average income. An Asian male apparently has a higher perceived value than a white male in higher paying technical fields.
Having an understanding of the reality and consistency of these patterns and your place within them will likely shape your opinion as to the validity and relevance of the income inequality issue.
Article Appeared @http://www.grenadastar.com/contentitem/398231/1218/education-race-gender-and-careers