the heritability of the number of fingers is very low, as variations in numbers of fingers are usually environmentally caused. The aforementioned earring example quoted by Chomsky is an instance where the opposite is true: high heritability, but not genetic determination. Given that genetic determination and heritability are not equivalent, Block contends that IQ is one such trait that is heritable but not genetically determined. Block cites the fact that IQ has not been constant as evidence, namely the increase of approximately 15 points of IQ across the world after World War 2 (around the same gap between blacks and whites), something that Murray himself notes in The Bell Curve. Since this is the case, the conclusions that Murray draws are based on equivocating between genetic determination and heritability, which Block criticizes as intellectually dishonest. Finally, Block contends that utilizing twin studies to randomize the environment automatically fail: Black twins will always bring a part of their environment with them as they are both Black and will be treated as such. Canadian psychologist Sidney Segalowitz concurs with Block that twin studies fail to draw conclusions about heritability, and as a result Murray's work is methodologically flawed. Statistical methods Claude S. Fischer, Michael Hout, Martín Sánchez Jankowski, Samuel R. Lucas, Ann Swidler, and Kim Voss in the book Inequality by Design recalculated the effect of socioeconomic status, using the same variables as The Bell Curve, but weighting them differently. They found that if IQ scores are adjusted, as Herrnstein and Murray did, to eliminate the effect of education, the ability of IQ to predict poverty can become dramatically larger, by as much as 61 percent for whites and 74 percent for blacks. According to the authors, Herrnstein and Murray's finding that IQ predicts poverty much better than socioeconomic status is substantially a result of the way they handled the statistics. In August 1995, National Bureau of Economic Research economist Sanders Korenman and Harvard University sociologist Christopher Winship argued that measurement error was not properly handled by Herrnstein and Murray. Korenman and Winship concluded: "...there is evidence of substantial bias due to measurement error in their estimates of the effects of parents' socioeconomic status. In addition, Herrnstein and Murray's measure of parental socioeconomic status (SES) fails to capture the effects of important elements of family background (such as single-parent family structure at age 14). As a result, their analysis gives an exaggerated