Looking for single causes, whether genetic or environmental, may yield answers of a kind, but little sense of what happens as each individual grows up. The language of nature versus nurture, or genes versus environment, gives only a feeble insight into the processes that I have called developmental cooking. The best that can be said of the nature/nurture split is that it provides a framework for uncovering a few of the genetic and environmental ingredients that generate differences between people. At worst, it satisfies a demand for simplicity in ways that are fundamentally misleading.