  Besides these attempts to reduce species to beanbags of genes, genetic reductionism enters in attempts to explain cellular or organismal properties solely in terms of genes, or entire organisms in terms of genomes. Gilbert (1992) endorses an essentialism of this sort as well: “The information carried on the DNA, that genetic information passed down from our parents,” he writes, “is the most fundamental property of the body” (p. 83), so much so, in fact, that “one will be able to pull a CD out of one's pocket and say, ‘Here is a human being; it's me!’” (p. 96). The social prevalence of this representation of the genome as the “most fundamental” aspect of the individual means that genetic information has a particularly acute impact on self-identity and self-understanding (Quaid 1994). Another genome scientist Eric Lander (1996) characterizes the HGP as “the 20th century's version of the discovery and consolidation of the periodic table” with the genes “elements” and gene variants responsible for disease susceptibilities “isotopes” (pp. 536–537). The probable social consequence of this beanbag conception of the organism, combined with a concept of genetic disease that relocates the locus of disease from organism to genome, is the direction of technological fixes at the genome (Keller 1994). When these technological fixes include prenatal genetic screening and the possible modification of IVF embryos, it is suggested that genetic reductionism contributes to the commodification of children by making them an instrument of parental desire (Darnovsky 2001). The relevant notion of “reduction” at play here is the explanation of wholes in terms of parts. As Sahotra Sarkar (1998) notes, it is important to distinguish between genetic reductionism and physical reductionism: “From the point of view of physical reductionism, DNA enters the molecular milieu on par with proteins or, for that matter, lipids or any other molecules that are found in living organisms. Physical reductionism does not require any assumption about the primacy of DNA or of genes in the explanation of biological behavior” (p. 174). The reduction of organisms to their genomes by molecular geneticists takes yet further molecular biology's—and, more generally, proximate biology's—reduction of organisms to their constituent physical parts in a way that effaces the contexts (provided by populations and environments) in which organisms develop (Griesemer 1994). Definitions of health and disease attach to organisms and their physiological processes in particular environments and cannot simply be relocated to the level of the genome (Limoges 1994; Lloyd 1994). It is wrong to presume that diseases become more objectively defined entities once they receive a genetic basis since social and cultural values implicated in designations of health and disease can merely become incorporated at the level of the genome, in what counts as a normal or mutant gene.