Differences in Intellectual Functioning

How does the IQ of low SES (socioeconomic status) children compare with middle- or upper-class children?
How does the IQ of African-American children compare to European American age mates? How do Latina, Latino, and Native Americans perform with regard to IQ scores?
Research suggests that parental encouragement and supervision in combination with peer support for academic achievement help explain the differences in ethnic groups. Explain and support this basis.