  Keller's account of the history of twentieth century genetics seems to reinforce gene skepticism. For example, she argues that the question about what genes are for has become increasingly difficult to answer (Keller 2000). By the end of the twentieth century, she says, biological findings have revealed a complexity of developmental dynamics that make it impossible to conceive of genes as distinct causal agents in development. Keller emphasizes that words have power and devotes a good deal of attention to the way loose gene talk has affected biological research by reinforcing the assumption that the gene is “the core explanatory concept of biological structure and function” (Keller 2000, p. 9), an assumption with which she strongly disagrees. Yet Keller does not endorse the view of gene skeptics who argue that biology would be improved if biologists stopped talking about “genes” and restricted themselves to terms designating molecular units such as nucleotide, codon, coding region, promotor region, and so on. Keller maintains that the term gene continues to have “obvious and undeniable uses.”