standard deviation above the population mean of 100. The biological children of these parents were also tested. The sample of adopted children was selected by eligible parents contacting the researchers for participating following a newsletter call. The geographical origin of the adopted children was not uniform. All except one white adopted child was adopted in-state. Black and interracial children came from twelve states; Asian and indigenous American children came from Minnesota as well as from Korea, Vietnam, Canada and Ecuador. As Scarr & Weinberg (1976) note, transracial adoption studies only control for family environment, not social environment. For example, children who are socially identified as black may still be subject to racial discrimination despite being raised by white parents. Yet, it was previously known that adoption into upper-middle class white families has a positive influence on the IQ and school performance of white children. The study showed significant differences in adoption patterns of mixed-race black/white and black adopted children as was noted by Scarr and Weinberg (1976): Results The children were first tested in 1975 at age 7. In 1985, 196 of the original 265 children were retested at age 17. The data showed mixed adoptees scoring slightly lower than white adoptees with gaps of 3 and 7 points at ages 7 and 17, while black adoptees scored 15 and 17 points below white adoptees at ages 7 and 17. The adopting parents of 12 of the interracial children wrongly believed that their adopted children had two black parents. The average IQ of these 12 children was not significantly different from the scores of the 56 interracial children correctly classified by their adoptive parents as having one black and one white parent. Some have suggested that differing pre-adoption experiences, including age at adoption, explain the racial patterns in the results. Lee (2009) argues against this interpretation, saying that there is no evidence from other studies that variables such as age at adoption exert an effect on IQ lasting until late adolescence. In the Minnesota study, the proportion of IQ variance associated with pre-adoption variables declined from .32 to .13 between ages 7 and 17. The average difference in IQ scores between the testing at age 7 and testing at age 17, seen in all groups, may be due to the use of different IQ tests. The original study used Stanford–Binet Form L-M, WISC or WAIS tests, depending on age, while