Waldman, Weinberg, and Scarr responded to Levin and Lynn. They noted that the data taken of adoption placement effects can explain the observed differences but that they cannot make that claim firmly because the pre-adoption factors confounded racial ancestry, preventing an unambiguous interpretation of the results. They also note that Asian data fit that hypothesis while being omitted by both Levin and Lynn. They argued that, "contrary to Levin's and Lynn's assertions, results from the Minnesota Transracial Adoption Study provide little or no conclusive evidence for genetic influences underlying racial differences in intelligence and achievement, " and noted that, "We think that it is exceedingly implausible that these differences are either entirely genetically based or entirely environmentally based. The true causes of racial-group differences in IQ, or in any other characteristic, are likely to be too complex to be captured by locating them on a single hereditarianism-environmentalism dimension."