Those political scientists who engage in this kind of research have only two choices in responding to Charney. Either they must deny Charney's claim that these six assumptions are necessary for their research. Or they must deny his claim that these assumptions have been refuted by recent research in molecular biology.
So, for instance, according to Charney, the first assumption of heritability studies is that "100% of the genes of MZ [monozygotic] twins are identical; on average, 50% of the genes of DZ [dizygotic] twins and singletons are identical; singletons possess ~50% of their parental DNA." But, in fact, Charney argues, biological research shows that this assumption is false. If Charney is wrong, he is either wrong in his formulation of the assumption, or he is wrong in thinking that the assumption is contrary to the biological research.
In one passage in his BBS article (at the beginning of sec. 6, page 38), Charney writes:
All of this places in doubt the validity of heritability estimates in all but a small class of traits (i.e., so-called "monogenic" disorders; see below, sec. 8.1). What this does not call into doubt, however, is the following: MZ twins are significantly more genetically concordant than DZ twins (and are likely most concordant in relation to single nucleotide polymorphisms), and this greater genetic concordance plays an important role in a wide range of inter-twin phenotypic concordances. As we shall see, however, this fact may end up being of limited practical application, at least within the framework of the conventional genetic paradigm.Should the proponents of heritability studies of political behavior see this as a crucial concession from Charney? If the latest research in molecular biology still supports the "greater genetic concordance" of MZ twins as compared with DZ twins, is this enough to sustain heritability studies? Or is Charney right that this has only "limited practical application" within the "genetic paradigm" that he is challenging?